Merge branch 'master' into fixes/1614-tile-brush-dpi-compatibility

.ncrunch/Avalonia.Native.v3.ncrunchproject

@@ -0,0 +1,5 @@
+<ProjectConfiguration>
+  <Settings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
+  </Settings>
+</ProjectConfiguration>

samples/ControlCatalog/MainView.xaml

@@ -1,33 +1,41 @@
 <UserControl xmlns="https://github.com/avaloniaui"
         xmlns:pages="clr-namespace:ControlCatalog.Pages"
-        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-  <TabControl Classes="sidebar" Name="Sidebar">
+        Background="{DynamicResource ThemeBackgroundBrush}"
-    <TabControl.PageTransition>
+        Foreground="{DynamicResource ThemeForegroundBrush}"
-      <CrossFade Duration="0.25"/>
+        FontSize="{DynamicResource FontSizeNormal}">
-    </TabControl.PageTransition>
+  <Grid>
-    <TabItem Header="AutoCompleteBox"><pages:AutoCompleteBoxPage/></TabItem>
+    <DropDown x:Name="Themes" SelectedIndex="0" Width="100" Margin="8" HorizontalAlignment="Right" VerticalAlignment="Bottom">
-    <TabItem Header="Border"><pages:BorderPage/></TabItem>
+      <DropDownItem>Light</DropDownItem>
-    <TabItem Header="Button"><pages:ButtonPage/></TabItem>
+      <DropDownItem>Dark</DropDownItem>
-    <TabItem Header="ButtonSpinner"><pages:ButtonSpinnerPage/></TabItem>
+    </DropDown>
-    <TabItem Header="Calendar"><pages:CalendarPage/></TabItem>
+    <TabControl Classes="sidebar" Name="Sidebar">
-    <TabItem Header="Canvas"><pages:CanvasPage/></TabItem>
+      <TabItem Header="AutoCompleteBox"><pages:AutoCompleteBoxPage/></TabItem>
-    <TabItem Header="Carousel"><pages:CarouselPage/></TabItem>
+      <TabItem Header="Border"><pages:BorderPage/></TabItem>
-    <TabItem Header="CheckBox"><pages:CheckBoxPage/></TabItem>
+      <TabItem Header="Button"><pages:ButtonPage/></TabItem>
-    <TabItem Header="ContextMenu"><pages:ContextMenuPage/></TabItem>
+      <TabItem Header="ButtonSpinner"><pages:ButtonSpinnerPage/></TabItem>
-    <TabItem Header="DatePicker"><pages:DatePickerPage/></TabItem>
+      <TabItem Header="Calendar"><pages:CalendarPage/></TabItem>
-    <TabItem Header="Drag+Drop"><pages:DragAndDropPage/></TabItem>
+      <TabItem Header="Canvas"><pages:CanvasPage/></TabItem>
-    <TabItem Header="DropDown"><pages:DropDownPage/></TabItem>
+      <TabItem Header="Carousel"><pages:CarouselPage/></TabItem>
-    <TabItem Header="Expander"><pages:ExpanderPage/></TabItem>
+      <TabItem Header="CheckBox"><pages:CheckBoxPage/></TabItem>
-    <TabItem Header="Image"><pages:ImagePage/></TabItem>
+      <TabItem Header="ContextMenu"><pages:ContextMenuPage/></TabItem>
-    <TabItem Header="LayoutTransformControl"><pages:LayoutTransformControlPage/></TabItem>
+      <TabItem Header="DatePicker"><pages:DatePickerPage/></TabItem>
-    <TabItem Header="ListBox"><pages:ListBoxPage/></TabItem>
+      <TabItem Header="Drag+Drop"><pages:DragAndDropPage/></TabItem>
-    <TabItem Header="Menu"><pages:MenuPage/></TabItem>
+      <TabItem Header="DropDown"><pages:DropDownPage/></TabItem>
-	<TabItem Header="NumericUpDown"><pages:NumericUpDownPage/></TabItem>
+      <TabItem Header="Expander"><pages:ExpanderPage/></TabItem>
-    <TabItem Header="ProgressBar"><pages:ProgressBarPage/></TabItem>
+      <TabItem Header="Image"><pages:ImagePage/></TabItem>
-    <TabItem Header="RadioButton"><pages:RadioButtonPage/></TabItem>
+      <TabItem Header="LayoutTransformControl"><pages:LayoutTransformControlPage/></TabItem>
-    <TabItem Header="Slider"><pages:SliderPage/></TabItem>
+      <TabItem Header="ListBox"><pages:ListBoxPage/></TabItem>
-    <TabItem Header="TextBox"><pages:TextBoxPage/></TabItem>
+      <TabItem Header="Menu"><pages:MenuPage/></TabItem>
-    <TabItem Header="ToolTip"><pages:ToolTipPage/></TabItem>
+	  <TabItem Header="NumericUpDown"><pages:NumericUpDownPage/></TabItem>
-    <TabItem Header="TreeView"><pages:TreeViewPage/></TabItem>
+      <TabItem Header="ProgressBar"><pages:ProgressBarPage/></TabItem>
-  </TabControl>
+      <TabItem Header="RadioButton"><pages:RadioButtonPage/></TabItem>
+      <TabItem Header="Slider"><pages:SliderPage/></TabItem>
+      <TabItem Header="TextBox"><pages:TextBoxPage/></TabItem>
+      <TabItem Header="ToolTip"><pages:ToolTipPage/></TabItem>
+      <TabItem Header="TreeView"><pages:TreeViewPage/></TabItem>
+      <TabItem Header="TabControl"><pages:TabControlPage/></TabItem>
+      <TabItem Header="Viewbox"><pages:ViewboxPage/></TabItem>
+    </TabControl>
+  </Grid>
 </UserControl>

samples/ControlCatalog/MainView.xaml.cs

@@ -2,6 +2,7 @@ using System.Collections;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
+using Avalonia.Markup.Xaml.Styling;
 using Avalonia.Platform;
 using ControlCatalog.Pages;
 
@@ -27,6 +28,22 @@ namespace ControlCatalog
                 });
 
             }
+            var light = AvaloniaXamlLoader.Parse<StyleInclude>(@"<StyleInclude xmlns='https://github.com/avaloniaui' Source='resm:Avalonia.Themes.Default.Accents.BaseLight.xaml?assembly=Avalonia.Themes.Default'/>");
+            var dark = AvaloniaXamlLoader.Parse<StyleInclude>(@"<StyleInclude xmlns='https://github.com/avaloniaui' Source='resm:Avalonia.Themes.Default.Accents.BaseDark.xaml?assembly=Avalonia.Themes.Default'/>");
+            var themes = this.Find<DropDown>("Themes");
+            themes.SelectionChanged += (sender, e) =>
+            {
+                switch (themes.SelectedIndex)
+                {
+                    case 0:
+                        Styles[0] = light;
+                        break;
+                    case 1:
+                        Styles[0] = dark;
+                        break;
+                }
+            };
+            Styles.Add(light);
         }
 
         private void InitializeComponent()

samples/ControlCatalog/Pages/TabControlPage.xaml

@@ -0,0 +1,97 @@
+<UserControl xmlns="https://github.com/avaloniaui">
+    <DockPanel>
+        <TextBlock 
+            DockPanel.Dock="Top" 
+            Classes="h1"
+            Text="TabControl"
+            Margin="4">           
+        </TextBlock>
+        <TextBlock 
+            DockPanel.Dock="Top" 
+            Classes="h2"
+            Text="A tab control that displays a tab strip along with the content of the selected tab"
+            Margin="4">          
+        </TextBlock>
+        <Grid 
+            ColumnDefinitions="*,*" 
+            RowDefinitions="*,100">
+            <DockPanel
+                Grid.Column="0"
+                Margin="4">
+                <TextBlock
+                    DockPanel.Dock="Top"
+                    Classes="h1"
+                    Text="From Inline TabItems">
+                </TextBlock>
+                <TabControl
+                    Margin="0 16"
+                    TabStripPlacement="{Binding TabPlacement}">
+                    <TabItem Header="Arch">
+                        <StackPanel Orientation="Vertical" Spacing="8">
+                            <TextBlock>This is the first page in the TabControl.</TextBlock>
+                            <Image Source="resm:ControlCatalog.Assets.delicate-arch-896885_640.jpg" Width="300"/>
+                        </StackPanel>
+                    </TabItem>
+                    <TabItem Header="Leaf">                       
+                        <StackPanel Orientation="Vertical" Spacing="8">
+                            <TextBlock>This is the second page in the TabControl.</TextBlock>
+                            <Image Source="resm:ControlCatalog.Assets.maple-leaf-888807_640.jpg" Width="300"/>
+                        </StackPanel>
+                    </TabItem>
+                    <TabItem Header="Disabled" IsEnabled="False">
+                        <TextBlock>You should not see this.</TextBlock>
+                    </TabItem>
+                </TabControl>
+            </DockPanel>
+            <DockPanel
+                Grid.Column="1"
+                Margin="4">
+                <TextBlock
+                    DockPanel.Dock="Top"
+                    Classes="h1"
+                    Text="From DataTemplate">
+                </TextBlock>
+                <TabControl
+                    Items="{Binding Tabs}"
+                    Margin="0 16"
+                    TabStripPlacement="{Binding TabPlacement}">
+                    <TabControl.ItemTemplate>
+                        <DataTemplate>
+                            <TextBlock
+                                Text="{Binding Header}">
+                            </TextBlock>
+                        </DataTemplate>
+                    </TabControl.ItemTemplate>
+                    <TabControl.ContentTemplate>
+                        <DataTemplate>
+                            <StackPanel Orientation="Vertical" Spacing="8">
+                                <TextBlock Text="{Binding Text}"/>
+                                <Image Source="{Binding Image}" Width="300"/>
+                            </StackPanel>
+                        </DataTemplate>
+                    </TabControl.ContentTemplate>
+                    <TabControl.Styles>
+                        <Style Selector="TabItem">
+                            <Setter Property="IsEnabled" Value="{Binding IsEnabled}"/>
+                        </Style>
+                    </TabControl.Styles>
+                </TabControl>
+            </DockPanel>
+            <StackPanel
+                Grid.Row="1"
+                Grid.ColumnSpan="2"
+                Orientation="Horizontal"
+                Spacing="8"
+                HorizontalAlignment="Center"
+                VerticalAlignment="Center">
+                <TextBlock VerticalAlignment="Center">Tab Placement:</TextBlock>
+                <DropDown SelectedIndex="{Binding TabPlacement, Mode=TwoWay}">
+                    <DropDownItem>Left</DropDownItem>
+                    <DropDownItem>Bottom</DropDownItem>
+                    <DropDownItem>Right</DropDownItem>
+                    <DropDownItem>Top</DropDownItem>
+                </DropDown>
+            </StackPanel>
+        </Grid>
+    </DockPanel>
+</UserControl>

samples/ControlCatalog/Pages/TabControlPage.xaml.cs

@@ -0,0 +1,80 @@
+using System;
+
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using Avalonia.Media.Imaging;
+using Avalonia.Platform;
+
+using ReactiveUI;
+
+namespace ControlCatalog.Pages
+{
+    using System.Collections.Generic;
+
+    public class TabControlPage : UserControl
+    {
+        public TabControlPage()
+        {
+            InitializeComponent();
+
+            DataContext = new PageViewModel
+            {
+                Tabs = new[]
+                {
+                    new TabItemViewModel
+                    {
+                        Header = "Arch",
+                        Text = "This is the first templated tab page.",
+                        Image = LoadBitmap("resm:ControlCatalog.Assets.delicate-arch-896885_640.jpg?assembly=ControlCatalog"),
+                    },
+                    new TabItemViewModel
+                    {
+                        Header = "Leaf",
+                        Text = "This is the second templated tab page.",
+                        Image = LoadBitmap("resm:ControlCatalog.Assets.maple-leaf-888807_640.jpg?assembly=ControlCatalog"),
+                    },
+                    new TabItemViewModel
+                    {
+                        Header = "Disabled",
+                        Text = "You should not see this.",
+                        IsEnabled = false,
+                    },
+                },
+                TabPlacement = Dock.Top,
+            };
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+
+        private IBitmap LoadBitmap(string uri)
+        {
+            var assets = AvaloniaLocator.Current.GetService<IAssetLoader>();
+            return new Bitmap(assets.Open(new Uri(uri)));
+        }
+
+        private class PageViewModel : ReactiveObject
+        {
+            private Dock _tabPlacement;
+
+            public TabItemViewModel[] Tabs { get; set; }
+
+            public Dock TabPlacement
+            {
+                get { return _tabPlacement; }
+                set { this.RaiseAndSetIfChanged(ref _tabPlacement, value); }
+            }
+        }
+
+        private class TabItemViewModel
+        {
+            public string Header { get; set; }
+            public string Text { get; set; }
+            public IBitmap Image { get; set; }
+            public bool IsEnabled { get; set; } = true;           
+        }
+    }
+}

samples/ControlCatalog/Pages/ViewboxPage.xaml

@@ -0,0 +1,65 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+    <UserControl.Resources>
+        <StreamGeometry x:Key="Acorn">
+            F1 M 16.6309,18.6563C 17.1309,
+            8.15625 29.8809,14.1563 29.8809,
+            14.1563C 30.8809,11.1563 34.1308,
+            11.4063 34.1308,11.4063C 33.5,12
+            34.6309,13.1563 34.6309,13.1563C
+            32.1309,13.1562 31.1309,14.9062
+            31.1309,14.9062C 41.1309,23.9062
+            32.6309,27.9063 32.6309,27.9062C
+            24.6309,24.9063 21.1309,22.1562
+            16.6309,18.6563 Z M 16.6309,19.9063C
+            21.6309,24.1563 25.1309,26.1562
+            31.6309,28.6562C 31.6309,28.6562
+            26.3809,39.1562 18.3809,36.1563C
+            18.3809,36.1563 18,38 16.3809,36.9063C
+            15,36 16.3809,34.9063 16.3809,34.9063C
+            16.3809,34.9063 10.1309,30.9062 16.6309,19.9063 Z
+        </StreamGeometry>
+    </UserControl.Resources>
+
+    <Grid RowDefinitions="Auto,*">
+        <StackPanel Orientation="Vertical" Spacing="4">
+            <TextBlock Classes="h1">Viewbox</TextBlock>
+            <TextBlock Classes="h2">A control used to scale single child.</TextBlock>
+        </StackPanel>
+        <Grid ColumnDefinitions="Auto,*,*"
+              RowDefinitions="*,*,*,*"
+              Grid.Row="1" Margin="48"
+              MaxWidth="400">
+            <TextBlock Grid.Row="0" VerticalAlignment="Center">None</TextBlock>
+            <TextBlock Grid.Row="1" VerticalAlignment="Center">Fill</TextBlock>
+            <TextBlock Grid.Row="2" VerticalAlignment="Center">Uniform</TextBlock>
+            <TextBlock Grid.Row="3" VerticalAlignment="Center">UniformToFill</TextBlock>
+
+            <Viewbox Grid.Row="0" Grid.Column="1" Stretch="None">
+                <TextBlock>Hello World!</TextBlock>
+            </Viewbox>
+            <Viewbox Grid.Row="1" Grid.Column="1" Stretch="Fill">
+                <TextBlock>Hello World!</TextBlock>
+            </Viewbox>
+            <Viewbox Grid.Row="2" Grid.Column="1" Stretch="Uniform">
+                <TextBlock>Hello World!</TextBlock>
+            </Viewbox>
+            <Viewbox Grid.Row="3" Grid.Column="1" Stretch="UniformToFill">
+                <TextBlock>Hello World!</TextBlock>
+            </Viewbox>
+
+            <Viewbox Grid.Row="0" Grid.Column="2" Stretch="None">
+                <Path Fill="Blue" Data="{StaticResource Acorn}"/>
+            </Viewbox>
+            <Viewbox Grid.Row="1" Grid.Column="2" Stretch="Fill">
+                <Path Fill="Blue" Data="{StaticResource Acorn}"/>
+            </Viewbox>
+            <Viewbox Grid.Row="2" Grid.Column="2" Stretch="Uniform">
+                <Path Fill="Blue" Data="{StaticResource Acorn}"/>
+            </Viewbox>
+            <Viewbox Grid.Row="3" Grid.Column="2" Stretch="UniformToFill">
+                <Path Fill="Blue" Data="{StaticResource Acorn}"/>
+            </Viewbox>
+        </Grid>
+    </Grid>
+</UserControl>

samples/ControlCatalog/Pages/ViewboxPage.xaml.cs

@@ -0,0 +1,18 @@
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace ControlCatalog.Pages
+{
+    public class ViewboxPage : UserControl
+    {
+        public ViewboxPage()
+        {
+            this.InitializeComponent();
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+    }
+}

samples/ControlCatalog/SideBar.xaml

@@ -1,52 +1,66 @@
 <Styles xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
-  <Style Selector="TabControl.sidebar">
+    <Style Selector="TabControl.sidebar">
-    <Setter Property="Template">
+        <Setter Property="TabStripPlacement" Value="Left"/>
-      <ControlTemplate>
+        <Setter Property="Padding" Value="8 0 0 0"/>
-        <DockPanel>
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush}"/>
-          <ScrollViewer MinWidth="190" Background="{DynamicResource ThemeAccentBrush}" DockPanel.Dock="Left">
+        <Setter Property="Template">
-            <TabStrip Name="PART_TabStrip"
+            <ControlTemplate>
-                      MemberSelector="{x:Static TabControl.HeaderSelector}"
+                <Border 
-                      Items="{TemplateBinding Items}"
+                    Margin="{TemplateBinding Margin}"
-                      SelectedIndex="{TemplateBinding SelectedIndex, Mode=TwoWay}">
+                    BorderBrush="{TemplateBinding BorderBrush}"
-              <TabStrip.ItemsPanel>
+                    BorderThickness="{TemplateBinding BorderThickness}">
-                <ItemsPanelTemplate>
+                    <DockPanel>
-                  <StackPanel Orientation="Vertical"/>
+                        <ScrollViewer
-                </ItemsPanelTemplate>
+                            Name="PART_ScrollViewer"
-              </TabStrip.ItemsPanel>
+                            HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
-            </TabStrip>
+                            VerticalScrollBarVisibility="{TemplateBinding (ScrollViewer.VerticalScrollBarVisibility)}"
-          </ScrollViewer>
+                            Background="{TemplateBinding Background}">
-          <Carousel Name="PART_Content"
+                            <ItemsPresenter
-                    Margin="8 0 0 0"
+                                Name="PART_ItemsPresenter"                          
-                    MemberSelector="{x:Static TabControl.ContentSelector}"
+                                Items="{TemplateBinding Items}"
-                    Items="{TemplateBinding Items}"
+                                ItemsPanel="{TemplateBinding ItemsPanel}"
-                    SelectedIndex="{TemplateBinding SelectedIndex}"
+                                ItemTemplate="{TemplateBinding ItemTemplate}"
-                    PageTransition="{TemplateBinding PageTransition}"
+                                MemberSelector="{TemplateBinding MemberSelector}">
-                    Grid.Row="1"/>
+                            </ItemsPresenter>
-        </DockPanel>
+                        </ScrollViewer>
-      </ControlTemplate>
+                        <ContentPresenter
-    </Setter>
+                            Name="PART_Content"
-  </Style>
+                            Margin="{TemplateBinding Padding}"                           
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                            Content="{TemplateBinding SelectedContent}"
+                            ContentTemplate="{TemplateBinding SelectedContentTemplate}">
+                        </ContentPresenter>
+                    </DockPanel>
+                </Border>
+            </ControlTemplate>
+        </Setter>
+    </Style>
 
-  <Style Selector="TabControl.sidebar TabStripItem">
+    <Style Selector="TabControl.sidebar > TabItem">       
-    <Setter Property="Foreground" Value="White"/>
+        <Setter Property="BorderThickness" Value="0"/>
-    <Setter Property="FontSize" Value="14"/>
+        <Setter Property="Foreground" Value="White"/>
-    <Setter Property="Margin" Value="0"/>
+        <Setter Property="FontSize" Value="14"/>
-    <Setter Property="Padding" Value="16"/>
+        <Setter Property="Margin" Value="0"/>
-    <Setter Property="Opacity" Value="0.5"/>
+        <Setter Property="Padding" Value="16"/>
-    <Setter Property="Transitions">
+        <Setter Property="Opacity" Value="0.5"/>
-      <Transitions>
+        <Setter Property="Transitions">
-        <DoubleTransition Property="Opacity" Duration="0:0:0.2"/>
+            <Transitions>
-      </Transitions>
+                <DoubleTransition Property="Opacity" Duration="0:0:0.5"/>
-    </Setter>
+            </Transitions>
-  </Style>
+        </Setter>
-
+    </Style>
-  <Style Selector="TabControl.sidebar TabStripItem:pointerover">
+    <Style Selector="TabControl.sidebar > TabItem:pointerover">
-    <Setter Property="Opacity" Value="1"/>
+        <Setter Property="Opacity" Value="1"/>
-  </Style>
+    </Style>
-
+    <Style Selector="TabControl.sidebar > TabItem:pointerover /template/ ContentPresenter#PART_ContentPresenter">
-  <Style Selector="TabControl.sidebar TabStripItem:selected">
+        <Setter Property="Background" Value="Transparent"/>
-    <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush2}"/>
+    </Style>
-    <Setter Property="Opacity" Value="1"/>
+    <Style Selector="TabControl.sidebar > TabItem:selected">
-  </Style>
+        <Setter Property="Opacity" Value="1"/>
+    </Style>
+    <Style Selector="TabControl.sidebar > TabItem:selected /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush2}"/>
+    </Style>
 </Styles>

samples/RenderDemo/MainWindow.xaml

@@ -24,9 +24,6 @@
       </MenuItem>
     </Menu>
     <TabControl Classes="sidebar">
-      <TabControl.PageTransition>
-        <CrossFade Duration="0.25"/>
-      </TabControl.PageTransition>
       <TabItem Header="Animations">
         <pages:AnimationsPage/>
       </TabItem>
@@ -38,4 +35,4 @@
       </TabItem>
     </TabControl>
   </DockPanel>
-</Window>
+</Window>

samples/RenderDemo/SideBar.xaml

@@ -1,53 +1,66 @@
 <Styles xmlns="https://github.com/avaloniaui"
-        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
-        xmlns:a="clr-namespace:Avalonia.Media.Animations;assembly=Avalonia.Media.Animations">
+    <Style Selector="TabControl.sidebar">
-  <Style Selector="TabControl.sidebar">
+        <Setter Property="TabStripPlacement" Value="Left"/>
-    <Setter Property="Template">
+        <Setter Property="Padding" Value="8 0 0 0"/>
-      <ControlTemplate>
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush}"/>
-        <DockPanel>
+        <Setter Property="Template">
-          <ScrollViewer MinWidth="190" Background="{DynamicResource ThemeAccentBrush}" DockPanel.Dock="Left">
+            <ControlTemplate>
-            <TabStrip Name="PART_TabStrip"
+                <Border 
-                      MemberSelector="{x:Static TabControl.HeaderSelector}"
+                    Margin="{TemplateBinding Margin}"
-                      Items="{TemplateBinding Items}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
-                      SelectedIndex="{TemplateBinding SelectedIndex, Mode=TwoWay}">
+                    BorderThickness="{TemplateBinding BorderThickness}">
-              <TabStrip.ItemsPanel>
+                    <DockPanel>
-                <ItemsPanelTemplate>
+                        <ScrollViewer
-                  <StackPanel Orientation="Vertical"/>
+                            Name="PART_ScrollViewer"
-                </ItemsPanelTemplate>
+                            HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
-              </TabStrip.ItemsPanel>
+                            VerticalScrollBarVisibility="{TemplateBinding (ScrollViewer.VerticalScrollBarVisibility)}"
-            </TabStrip>
+                            Background="{TemplateBinding Background}">
-          </ScrollViewer>
+                            <ItemsPresenter
-          <Carousel Name="PART_Content"
+                                Name="PART_ItemsPresenter"                                                            
-                    Margin="8 0 0 0"
+                                Items="{TemplateBinding Items}"
-                    MemberSelector="{x:Static TabControl.ContentSelector}"
+                                ItemsPanel="{TemplateBinding ItemsPanel}"
-                    Items="{TemplateBinding Items}"
+                                ItemTemplate="{TemplateBinding ItemTemplate}"
-                    SelectedIndex="{TemplateBinding SelectedIndex}"
+                                MemberSelector="{TemplateBinding MemberSelector}">
-                    PageTransition="{TemplateBinding PageTransition}"
+                            </ItemsPresenter>
-                    Grid.Row="1"/>
+                        </ScrollViewer>
-        </DockPanel>
+                        <ContentPresenter
-      </ControlTemplate>
+                            Name="PART_Content"
-    </Setter>
+                            Margin="{TemplateBinding Padding}"                           
-  </Style>
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                            Content="{TemplateBinding SelectedContent}"
+                            ContentTemplate="{TemplateBinding SelectedContentTemplate}">
+                        </ContentPresenter>
+                    </DockPanel>
+                </Border>
+            </ControlTemplate>
+        </Setter>
+    </Style>
 
-  <Style Selector="TabControl.sidebar TabStripItem">
+    <Style Selector="TabControl.sidebar > TabItem">       
-    <Setter Property="Foreground" Value="White"/>
+        <Setter Property="BorderThickness" Value="0"/>
-    <Setter Property="FontSize" Value="14"/>
+        <Setter Property="Foreground" Value="White"/>
-    <Setter Property="Margin" Value="0"/>
+        <Setter Property="FontSize" Value="14"/>
-    <Setter Property="Padding" Value="16"/>
+        <Setter Property="Margin" Value="0"/>
-    <Setter Property="Opacity" Value="0.5"/>
+        <Setter Property="Padding" Value="16"/>
-    <Setter Property="Transitions">
+        <Setter Property="Opacity" Value="0.5"/>
-      <Transitions>
+        <Setter Property="Transitions">
-        <DoubleTransition Property="Opacity" Duration="0:0:0.2"/>
+            <Transitions>
-      </Transitions>
+                <DoubleTransition Property="Opacity" Duration="0:0:0.5"/>
-    </Setter>
+            </Transitions>
-  </Style>
+        </Setter>
-
+    </Style>
-  <Style Selector="TabControl.sidebar TabStripItem:pointerover">
+    <Style Selector="TabControl.sidebar > TabItem:pointerover">
-    <Setter Property="Opacity" Value="1"/>
+        <Setter Property="Opacity" Value="1"/>
-  </Style>
+    </Style>
-
+    <Style Selector="TabControl.sidebar > TabItem:pointerover /template/ ContentPresenter#PART_ContentPresenter">
-  <Style Selector="TabControl.sidebar TabStripItem:selected">
+        <Setter Property="Background" Value="Transparent"/>
-    <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush2}"/>
+    </Style>
-    <Setter Property="Opacity" Value="1"/>
+    <Style Selector="TabControl.sidebar > TabItem:selected">
-  </Style>
+        <Setter Property="Opacity" Value="1"/>
+    </Style>
+    <Style Selector="TabControl.sidebar > TabItem:selected /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush2}"/>
+    </Style>
 </Styles>

src/Avalonia.Base/Data/Core/ExpressionNode.cs

@@ -88,18 +88,21 @@ namespace Avalonia.Data.Core
             _subscriber(value);
         }
 
-        protected void ValueChanged(object value)
+        protected void ValueChanged(object value) => ValueChanged(value, true);
+
+        private void ValueChanged(object value, bool notify)
         {
             var notification = value as BindingNotification;
 
             if (notification == null)
             {
                 LastValue = new WeakReference(value);
+
                 if (Next != null)
                 {
-                    Next.Target = new WeakReference(value);
+                    Next.Target = LastValue;
                 }
-                else
+                else if (notify)
                 {
                     _subscriber(value);
                 }
@@ -110,7 +113,7 @@ namespace Avalonia.Data.Core
 
                 if (Next != null)
                 {
-                    Next.Target = new WeakReference(notification.Value);
+                    Next.Target = LastValue;
                 }
 
                 if (Next == null || notification.Error != null)
@@ -136,6 +139,7 @@ namespace Avalonia.Data.Core
             }
             else
             {
+                ValueChanged(AvaloniaProperty.UnsetValue, notify:false);
                 _listening = false;
             }
         }

src/Avalonia.Controls/DropDown.cs

@@ -2,9 +2,12 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Linq;
 using Avalonia.Controls.Generators;
+using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
+using Avalonia.Controls.Templates;
 using Avalonia.Input;
 using Avalonia.LogicalTree;
 using Avalonia.Media;
@@ -12,12 +15,17 @@ using Avalonia.VisualTree;
 
 namespace Avalonia.Controls
 {
-
     /// <summary>
     /// A drop-down list control.
     /// </summary>
     public class DropDown : SelectingItemsControl
     {
+        /// <summary>
+        /// The default value for the <see cref="ItemsControl.ItemsPanel"/> property.
+        /// </summary>
+        private static readonly FuncTemplate<IPanel> DefaultPanel =
+            new FuncTemplate<IPanel>(() => new VirtualizingStackPanel());
+
         /// <summary>
         /// Defines the <see cref="IsDropDownOpen"/> property.
         /// </summary>
@@ -39,6 +47,12 @@ namespace Avalonia.Controls
         public static readonly DirectProperty<DropDown, object> SelectionBoxItemProperty =
             AvaloniaProperty.RegisterDirect<DropDown, object>(nameof(SelectionBoxItem), o => o.SelectionBoxItem);
 
+        /// <summary>
+        /// Defines the <see cref="VirtualizationMode"/> property.
+        /// </summary>
+        public static readonly StyledProperty<ItemVirtualizationMode> VirtualizationModeProperty =
+            ItemsPresenter.VirtualizationModeProperty.AddOwner<DropDown>();
+
         private bool _isDropDownOpen;
         private Popup _popup;
         private object _selectionBoxItem;
@@ -48,6 +62,7 @@ namespace Avalonia.Controls
         /// </summary>
         static DropDown()
         {
+            ItemsPanelProperty.OverrideDefaultValue<DropDown>(DefaultPanel);
             FocusableProperty.OverrideDefaultValue<DropDown>(true);
             SelectedItemProperty.Changed.AddClassHandler<DropDown>(x => x.SelectedItemChanged);
             KeyDownEvent.AddClassHandler<DropDown>(x => x.OnKeyDown, Interactivity.RoutingStrategies.Tunnel);
@@ -80,6 +95,15 @@ namespace Avalonia.Controls
             set { SetAndRaise(SelectionBoxItemProperty, ref _selectionBoxItem, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the virtualization mode for the items.
+        /// </summary>
+        public ItemVirtualizationMode VirtualizationMode
+        {
+            get { return GetValue(VirtualizationModeProperty); }
+            set { SetValue(VirtualizationModeProperty, value); }
+        }
+
         /// <inheritdoc/>
         protected override IItemContainerGenerator CreateItemContainerGenerator()
         {
@@ -138,6 +162,16 @@ namespace Avalonia.Controls
                     e.Handled = true;
                 }
             }
+            else if (IsDropDownOpen && SelectedIndex < 0 && ItemCount > 0 &&
+                      (e.Key == Key.Up || e.Key == Key.Down))
+            {
+                var firstChild = Presenter?.Panel?.Children.FirstOrDefault(c => CanFocus(c));
+                if (firstChild != null)
+                {
+                    FocusManager.Instance?.Focus(firstChild, NavigationMethod.Directional);
+                    e.Handled = true;
+                }
+            }
         }
 
         /// <inheritdoc/>
@@ -159,6 +193,7 @@ namespace Avalonia.Controls
                     e.Handled = true;
                 }
             }
+
             base.OnPointerPressed(e);
         }
 
@@ -168,28 +203,65 @@ namespace Avalonia.Controls
             if (_popup != null)
             {
                 _popup.Opened -= PopupOpened;
+                _popup.Closed -= PopupClosed;
             }
 
             _popup = e.NameScope.Get<Popup>("PART_Popup");
             _popup.Opened += PopupOpened;
+            _popup.Closed += PopupClosed;
+
+            base.OnTemplateApplied(e);
         }
 
-        private void PopupOpened(object sender, EventArgs e)
+        internal void ItemFocused(DropDownItem dropDownItem)
         {
-            var selectedIndex = SelectedIndex;
+            if (IsDropDownOpen && dropDownItem.IsFocused && dropDownItem.IsArrangeValid)
+            {
+                dropDownItem.BringIntoView();
+            }
+        }
 
-            if (selectedIndex != -1)
+        private void PopupClosed(object sender, EventArgs e)
+        {
+            if (CanFocus(this))
             {
-                var container = ItemContainerGenerator.ContainerFromIndex(selectedIndex);
+                Focus();
-                container?.Focus();
             }
         }
 
+        private void PopupOpened(object sender, EventArgs e)
+        {
+            TryFocusSelectedItem();
+        }
+
         private void SelectedItemChanged(AvaloniaPropertyChangedEventArgs e)
         {
             UpdateSelectionBoxItem(e.NewValue);
+            TryFocusSelectedItem();
+        }
+
+        private void TryFocusSelectedItem()
+        {
+            var selectedIndex = SelectedIndex;
+            if (IsDropDownOpen && selectedIndex != -1)
+            {
+                var container = ItemContainerGenerator.ContainerFromIndex(selectedIndex);
+
+                if(container == null && SelectedItems.Count > 0)
+                {
+                    ScrollIntoView(SelectedItems[0]);
+                    container = ItemContainerGenerator.ContainerFromIndex(selectedIndex);
+                }
+
+                if (container != null && CanFocus(container))
+                {
+                    container.Focus();
+                }
+            }
         }
 
+        private bool CanFocus(IControl control) => control.Focusable && control.IsEnabledCore && control.IsVisible;
+
         private void UpdateSelectionBoxItem(object item)
         {
             var contentControl = item as IContentControl;
@@ -219,7 +291,8 @@ namespace Avalonia.Controls
             }
             else
             {
-                SelectionBoxItem = item;
+                var selector = MemberSelector;
+                SelectionBoxItem = selector != null ? selector.Select(item) : item;
             }
         }
 

src/Avalonia.Controls/DropDownItem.cs

@@ -2,43 +2,19 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Reactive.Linq;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// A selectable item in a <see cref="DropDown"/>.
     /// </summary>
-    public class DropDownItem : ContentControl, ISelectable
+    public class DropDownItem : ListBoxItem
     {
-        /// <summary>
-        /// Defines the <see cref="IsSelected"/> property.
-        /// </summary>
-        public static readonly StyledProperty<bool> IsSelectedProperty =
-            AvaloniaProperty.Register<DropDownItem, bool>(nameof(IsSelected));
-
-        /// <summary>
-        /// Initializes static members of the <see cref="DropDownItem"/> class.
-        /// </summary>
-        static DropDownItem()
-        {
-            FocusableProperty.OverrideDefaultValue<DropDownItem>(true);
-        }
-
         public DropDownItem()
         {
-            this.GetObservable(DropDownItem.IsFocusedProperty).Subscribe(focused =>
+            this.GetObservable(DropDownItem.IsFocusedProperty).Where(focused => focused)
-            {
+                .Subscribe(_ => (Parent as DropDown)?.ItemFocused(this));
-                PseudoClasses.Set(":selected", focused);                
-            });
-        }
-
-        /// <summary>
-        /// Gets or sets the selection state of the item.
-        /// </summary>
-        public bool IsSelected
-        {
-            get { return GetValue(IsSelectedProperty); }
-            set { SetValue(IsSelectedProperty, value); }
         }
     }
 }

src/Avalonia.Controls/Generators/TabItemContainerGenerator.cs

@@ -0,0 +1,59 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Controls.Generators
+{    
+    public class TabItemContainerGenerator : ItemContainerGenerator<TabItem>
+    {
+        public TabItemContainerGenerator(TabControl owner)
+            : base(owner, ContentControl.ContentProperty, ContentControl.ContentTemplateProperty)
+        {
+            Owner = owner;
+        }
+
+        public new TabControl Owner { get; }
+
+        protected override IControl CreateContainer(object item)
+        {
+            var tabItem = (TabItem)base.CreateContainer(item);
+
+            tabItem.ParentTabControl = Owner;
+
+            tabItem[~TabControl.TabStripPlacementProperty] = Owner[~TabControl.TabStripPlacementProperty];
+
+            if (tabItem.HeaderTemplate == null)
+            {
+                tabItem[~HeaderedContentControl.HeaderTemplateProperty] = Owner[~ItemsControl.ItemTemplateProperty];
+            }
+
+            if (tabItem.Header == null)
+            {
+                if (item is IHeadered headered)
+                {
+                    tabItem.Header = headered.Header;
+                }
+                else
+                {
+                    if (!(tabItem.DataContext is IControl))
+                    {
+                        tabItem.Header = tabItem.DataContext;
+                    }
+                }
+            }
+
+            if (!(tabItem.Content is IControl))
+            {
+                tabItem[~ContentControl.ContentTemplateProperty] = Owner[~TabControl.ContentTemplateProperty];
+            }
+
+            if (tabItem.Content == null)
+            {
+                tabItem[~ContentControl.ContentProperty] = tabItem[~StyledElement.DataContextProperty];
+            }
+
+            return tabItem;
+        }
+    }
+}

src/Avalonia.Controls/ItemsControl.cs

@@ -249,8 +249,6 @@ namespace Avalonia.Controls
                         if (containerControl != null)
                         {
                             ((ISetLogicalParent)containerControl).SetParent(this);
-                            containerControl.SetValue(TemplatedParentProperty, null);
-
                             containerControl.UpdateChild();
 
                             if (containerControl.Child != null)

src/Avalonia.Controls/LayoutTransformControl.cs

@@ -5,28 +5,30 @@
 // http://silverlight.codeplex.com/SourceControl/changeset/view/74775#Release/Silverlight4/Source/Controls.Layout.Toolkit/LayoutTransformer/LayoutTransformer.cs
 //
 
-using Avalonia.Controls.Primitives;
-using Avalonia.Media;
-using Avalonia.VisualTree;
 using System;
 using System.Diagnostics.CodeAnalysis;
-using System.Linq;
 using System.Reactive.Linq;
+using Avalonia.Media;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// Control that implements support for transformations as if applied by LayoutTransform.
     /// </summary>
-    public class LayoutTransformControl : ContentControl
+    public class LayoutTransformControl : Decorator
     {
         public static readonly AvaloniaProperty<Transform> LayoutTransformProperty =
             AvaloniaProperty.Register<LayoutTransformControl, Transform>(nameof(LayoutTransform));
 
         static LayoutTransformControl()
         {
+            ClipToBoundsProperty.OverrideDefaultValue<LayoutTransformControl>(true);
+
             LayoutTransformProperty.Changed
                 .AddClassHandler<LayoutTransformControl>(x => x.OnLayoutTransformChanged);
+
+            ChildProperty.Changed
+                .AddClassHandler<LayoutTransformControl>(x => x.OnChildChanged);
         }
 
         /// <summary>
@@ -38,8 +40,7 @@ namespace Avalonia.Controls
             set { SetValue(LayoutTransformProperty, value); }
         }
 
-        public Control TransformRoot => _transformRoot ??
+        public IControl TransformRoot => Child;
-                            (_transformRoot = this.GetVisualChildren().OfType<Control>().FirstOrDefault());
 
         /// <summary>
         /// Provides the behavior for the "Arrange" pass of layout.
@@ -132,16 +133,8 @@ namespace Avalonia.Controls
             return transformedDesiredSize;
         }
 
-        /// <summary>
+        private void OnChildChanged(AvaloniaPropertyChangedEventArgs e)
-        /// Builds the visual tree for the LayoutTransformerControl when a new
-        /// template is applied.
-        /// </summary>
-        protected override void OnTemplateApplied(TemplateAppliedEventArgs e)
         {
-            base.OnTemplateApplied(e);
-
-            _matrixTransform = new MatrixTransform();
-
             if (null != TransformRoot)
             {
                 TransformRoot.RenderTransform = _matrixTransform;
@@ -169,14 +162,14 @@ namespace Avalonia.Controls
         /// <summary>
         /// RenderTransform/MatrixTransform applied to TransformRoot.
         /// </summary>
-        private MatrixTransform _matrixTransform;
+        private MatrixTransform _matrixTransform = new MatrixTransform();
 
         /// <summary>
         /// Transformation matrix corresponding to _matrixTransform.
         /// </summary>
         private Matrix _transformation;
         private IDisposable _transformChangedEvent = null;
-        private Control _transformRoot;
+
         /// <summary>
         /// Returns true if Size a is smaller than Size b in either dimension.
         /// </summary>
@@ -215,7 +208,8 @@ namespace Avalonia.Controls
         /// </remarks>
         private void ApplyLayoutTransform()
         {
-            if (LayoutTransform == null) return;
+            if (LayoutTransform == null)
+                return;
 
             // Get the transform matrix and apply it
             _transformation = RoundMatrix(LayoutTransform.Value, DecimalsAfterRound);
@@ -376,11 +370,8 @@ namespace Avalonia.Controls
         {
             var newTransform = e.NewValue as Transform;
 
-            if (_transformChangedEvent != null)
+            _transformChangedEvent?.Dispose();
-            {
+            _transformChangedEvent = null;
-                _transformChangedEvent.Dispose();
-                _transformChangedEvent = null;
-            }
 
             if (newTransform != null)
             {
@@ -392,4 +383,4 @@ namespace Avalonia.Controls
             ApplyLayoutTransform();
         }
     }
-}
+}

src/Avalonia.Controls/Primitives/HeaderedContentControl.cs

@@ -1,6 +1,8 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using Avalonia.Controls.Templates;
+
 namespace Avalonia.Controls.Primitives
 {
     /// <summary>
@@ -12,7 +14,13 @@ namespace Avalonia.Controls.Primitives
         /// Defines the <see cref="Header"/> property.
         /// </summary>
         public static readonly StyledProperty<object> HeaderProperty =
-            AvaloniaProperty.Register<ContentControl, object>(nameof(Header));
+            AvaloniaProperty.Register<HeaderedContentControl, object>(nameof(Header));
+
+        /// <summary>
+        /// Defines the <see cref="HeaderTemplate"/> property.
+        /// </summary>
+        public static readonly StyledProperty<IDataTemplate> HeaderTemplateProperty =
+            AvaloniaProperty.Register<HeaderedContentControl, IDataTemplate>(nameof(HeaderTemplate));          
 
         /// <summary>
         /// Gets or sets the header content.
@@ -21,6 +29,15 @@ namespace Avalonia.Controls.Primitives
         {
             get { return GetValue(HeaderProperty); }
             set { SetValue(HeaderProperty, value); }
+        }     
+
+        /// <summary>
+        /// Gets or sets the data template used to display the header content of the control.
+        /// </summary>
+        public IDataTemplate HeaderTemplate
+        {
+            get { return GetValue(HeaderTemplateProperty); }
+            set { SetValue(HeaderTemplateProperty, value); }
         }
     }
-}
+}

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -431,9 +431,12 @@ namespace Avalonia.Controls.Primitives
             {
                 if (i.ContainerControl != null && i.Item != null)
                 {
-                    MarkContainerSelected(
+                    var ms = MemberSelector;
-                        i.ContainerControl,
+                    bool selected = ms == null ? 
-                        SelectedItems.Contains(i.Item));
+                        SelectedItems.Contains(i.Item) : 
+                        SelectedItems.OfType<object>().Any(v => Equals(ms.Select(v), i.Item));
+
+                    MarkContainerSelected(i.ContainerControl, selected);
                 }
             }
         }

src/Avalonia.Controls/Primitives/TemplatedControl.cs

@@ -260,7 +260,7 @@ namespace Avalonia.Controls.Primitives
                     var child = template.Build(this);
                     var nameScope = new NameScope();
                     NameScope.SetNameScope((Control)child, nameScope);
-                    child.SetValue(TemplatedParentProperty, this);
+                    ApplyTemplatedParent(child);
                     RegisterNames(child, nameScope);
                     ((ISetLogicalParent)child).SetParent(this);
                     VisualChildren.Add(child);
@@ -326,6 +326,23 @@ namespace Avalonia.Controls.Primitives
             InvalidateMeasure();
         }
 
+        /// <summary>
+        /// Sets the TemplatedParent property for the created template children.
+        /// </summary>
+        /// <param name="control">The control.</param>
+        private void ApplyTemplatedParent(IControl control)
+        {
+            control.SetValue(TemplatedParentProperty, this);
+
+            foreach (var child in control.LogicalChildren)
+            {
+                if (child is IControl c)
+                {
+                    ApplyTemplatedParent(c);
+                }
+            }
+        }
+
         /// <summary>
         /// Registers each control with its name scope.
         /// </summary>

src/Avalonia.Controls/TabControl.cs

@@ -1,10 +1,12 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using Avalonia.Animation;
 using Avalonia.Controls.Generators;
+using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
+using Avalonia.Input;
+using Avalonia.Layout;
 
 namespace Avalonia.Controls
 {
@@ -14,28 +16,46 @@ namespace Avalonia.Controls
     public class TabControl : SelectingItemsControl
     {
         /// <summary>
-        /// Defines the <see cref="PageTransition"/> property.
+        /// Defines the <see cref="TabStripPlacement"/> property.
         /// </summary>
-        public static readonly StyledProperty<IPageTransition> PageTransitionProperty =
+        public static readonly StyledProperty<Dock> TabStripPlacementProperty =
-            Avalonia.Controls.Carousel.PageTransitionProperty.AddOwner<TabControl>();
+            AvaloniaProperty.Register<TabControl, Dock>(nameof(TabStripPlacement), defaultValue: Dock.Top);
 
         /// <summary>
-        /// Defines an <see cref="IMemberSelector"/> that selects the content of a <see cref="TabItem"/>.
+        /// Defines the <see cref="HorizontalContentAlignment"/> property.
         /// </summary>
-        public static readonly IMemberSelector ContentSelector =
+        public static readonly StyledProperty<HorizontalAlignment> HorizontalContentAlignmentProperty =
-            new FuncMemberSelector<object, object>(SelectContent);
+            ContentControl.HorizontalContentAlignmentProperty.AddOwner<TabControl>();
 
         /// <summary>
-        /// Defines an <see cref="IMemberSelector"/> that selects the header of a <see cref="TabItem"/>.
+        /// Defines the <see cref="VerticalContentAlignment"/> property.
         /// </summary>
-        public static readonly IMemberSelector HeaderSelector =
+        public static readonly StyledProperty<VerticalAlignment> VerticalContentAlignmentProperty =
-            new FuncMemberSelector<object, object>(SelectHeader);
+            ContentControl.VerticalContentAlignmentProperty.AddOwner<TabControl>();
 
         /// <summary>
-        /// Defines the <see cref="TabStripPlacement"/> property.
+        /// Defines the <see cref="ContentTemplate"/> property.
         /// </summary>
-        public static readonly StyledProperty<Dock> TabStripPlacementProperty =
+        public static readonly StyledProperty<IDataTemplate> ContentTemplateProperty =
-            AvaloniaProperty.Register<TabControl, Dock>(nameof(TabStripPlacement), defaultValue: Dock.Top);
+            ContentControl.ContentTemplateProperty.AddOwner<TabControl>();
+
+        /// <summary>
+        /// The selected content property
+        /// </summary>
+        public static readonly StyledProperty<object> SelectedContentProperty =
+            AvaloniaProperty.Register<TabControl, object>(nameof(SelectedContent));
+
+        /// <summary>
+        /// The selected content template property
+        /// </summary>
+        public static readonly StyledProperty<IDataTemplate> SelectedContentTemplateProperty =
+            AvaloniaProperty.Register<TabControl, IDataTemplate>(nameof(SelectedContentTemplate));
+
+        /// <summary>
+        /// The default value for the <see cref="ItemsControl.ItemsPanel"/> property.
+        /// </summary>
+        private static readonly FuncTemplate<IPanel> DefaultPanel =
+            new FuncTemplate<IPanel>(() => new WrapPanel());
 
         /// <summary>
         /// Initializes static members of the <see cref="TabControl"/> class.
@@ -43,107 +63,107 @@ namespace Avalonia.Controls
         static TabControl()
         {
             SelectionModeProperty.OverrideDefaultValue<TabControl>(SelectionMode.AlwaysSelected);
-            FocusableProperty.OverrideDefaultValue<TabControl>(false);
+            ItemsPanelProperty.OverrideDefaultValue<TabControl>(DefaultPanel);
             AffectsMeasure<TabControl>(TabStripPlacementProperty);
         }
 
         /// <summary>
-        /// Gets the pages portion of the <see cref="TabControl"/>'s template.
+        /// Gets or sets the horizontal alignment of the content within the control.
         /// </summary>
-        public IControl Pages
+        public HorizontalAlignment HorizontalContentAlignment
         {
-            get;
+            get { return GetValue(HorizontalContentAlignmentProperty); }
-            private set;
+            set { SetValue(HorizontalContentAlignmentProperty, value); }
         }
 
         /// <summary>
-        /// Gets the tab strip portion of the <see cref="TabControl"/>'s template.
+        /// Gets or sets the vertical alignment of the content within the control.
         /// </summary>
-        public IControl TabStrip
+        public VerticalAlignment VerticalContentAlignment
         {
-            get;
+            get { return GetValue(VerticalContentAlignmentProperty); }
-            private set;
+            set { SetValue(VerticalContentAlignmentProperty, value); }
         }
 
         /// <summary>
-        /// Gets or sets the transition to use when switching tabs.
+        /// Gets or sets the tabstrip placement of the TabControl.
         /// </summary>
-        public IPageTransition PageTransition
+        public Dock TabStripPlacement
         {
-            get { return GetValue(PageTransitionProperty); }
+            get { return GetValue(TabStripPlacementProperty); }
-            set { SetValue(PageTransitionProperty, value); }
+            set { SetValue(TabStripPlacementProperty, value); }
         }
 
         /// <summary>
-        /// Gets or sets the tabstrip placement of the tabcontrol.
+        /// Gets or sets the default data template used to display the content of the selected tab.
         /// </summary>
-        public Dock TabStripPlacement
+        public IDataTemplate ContentTemplate
         {
-            get { return GetValue(TabStripPlacementProperty); }
+            get { return GetValue(ContentTemplateProperty); }
-            set { SetValue(TabStripPlacementProperty, value); }
+            set { SetValue(ContentTemplateProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the content of the selected tab.
+        /// </summary>
+        /// <value>
+        /// The content of the selected tab.
+        /// </value>
+        public object SelectedContent
+        {
+            get { return GetValue(SelectedContentProperty); }
+            internal set { SetValue(SelectedContentProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the content template for the selected tab.
+        /// </summary>
+        /// <value>
+        /// The content template of the selected tab.
+        /// </value>
+        public IDataTemplate SelectedContentTemplate
+        {
+            get { return GetValue(SelectedContentTemplateProperty); }
+            internal set { SetValue(SelectedContentTemplateProperty, value); }
+        }
+
+        internal ItemsPresenter ItemsPresenterPart { get; private set; }
+
+        internal ContentPresenter ContentPart { get; private set; }
+
         protected override IItemContainerGenerator CreateItemContainerGenerator()
         {
-            // TabControl doesn't actually create items - instead its TabStrip and Carousel
+            return new TabItemContainerGenerator(this);
-            // children create the items. However we want it to be a SelectingItemsControl
-            // so that it has the Items/SelectedItem etc properties. In this case, we can
-            // return a null ItemContainerGenerator to disable the creation of item containers.
-            return null;
         }
 
         protected override void OnTemplateApplied(TemplateAppliedEventArgs e)
         {
             base.OnTemplateApplied(e);
 
-            TabStrip = e.NameScope.Find<IControl>("PART_TabStrip");
+            ItemsPresenterPart = e.NameScope.Get<ItemsPresenter>("PART_ItemsPresenter");
-            Pages = e.NameScope.Find<IControl>("PART_Content");
+
+            ContentPart = e.NameScope.Get<ContentPresenter>("PART_Content");
         }
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// Selects the content of a tab item.
+        protected override void OnGotFocus(GotFocusEventArgs e)
-        /// </summary>
-        /// <param name="o">The tab item.</param>
-        /// <returns>The content.</returns>
-        private static object SelectContent(object o)
         {
-            var content = o as IContentControl;
+            base.OnGotFocus(e);
 
-            if (content != null)
+            if (e.NavigationMethod == NavigationMethod.Directional)
             {
-                return content.Content;
+                e.Handled = UpdateSelectionFromEventSource(e.Source);
             }
-            else
-            {
-                return o;
-            }       
         }
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// Selects the header of a tab item.
+        protected override void OnPointerPressed(PointerPressedEventArgs e)
-        /// </summary>
-        /// <param name="o">The tab item.</param>
-        /// <returns>The content.</returns>
-        private static object SelectHeader(object o)
         {
-            var headered = o as IHeadered;
+            base.OnPointerPressed(e);
-            var control = o as IControl;
 
-            if (headered != null)
+            if (e.MouseButton == MouseButton.Left)
-            {
-                return headered.Header ?? string.Empty;
-            }
-            else if (control != null)
-            {
-                // Non-headered control items should result in TabStripItems with empty content.
-                // If a TabStrip is created with non IHeadered controls as its items, don't try to
-                // display the control in the TabStripItem: the content portion will also try to 
-                // display this control, resulting in dual-parentage breakage.
-                return string.Empty;
-            }
-            else
             {
-                return o;
+                e.Handled = UpdateSelectionFromEventSource(e.Source);
             }
         }
     }

src/Avalonia.Controls/TabItem.cs

@@ -11,6 +11,12 @@ namespace Avalonia.Controls
     /// </summary>
     public class TabItem : HeaderedContentControl, ISelectable
     {
+        /// <summary>
+        /// Defines the <see cref="TabStripPlacement"/> property.
+        /// </summary>
+        public static readonly StyledProperty<Dock> TabStripPlacementProperty =
+            TabControl.TabStripPlacementProperty.AddOwner<TabItem>();
+
         /// <summary>
         /// Defines the <see cref="IsSelected"/> property.
         /// </summary>
@@ -24,6 +30,19 @@ namespace Avalonia.Controls
         {
             SelectableMixin.Attach<TabItem>(IsSelectedProperty);
             FocusableProperty.OverrideDefaultValue(typeof(TabItem), true);
+            IsSelectedProperty.Changed.AddClassHandler<TabItem>(x => x.UpdateSelectedContent);
+            DataContextProperty.Changed.AddClassHandler<TabItem>(x => x.UpdateHeader);
+        }
+
+        /// <summary>
+        /// Gets the tab strip placement.
+        /// </summary>
+        /// <value>
+        /// The tab strip placement.
+        /// </value>
+        public Dock TabStripPlacement
+        {
+            get { return GetValue(TabStripPlacementProperty); }
         }
 
         /// <summary>
@@ -34,5 +53,53 @@ namespace Avalonia.Controls
             get { return GetValue(IsSelectedProperty); }
             set { SetValue(IsSelectedProperty, value); }
         }
+
+        internal TabControl ParentTabControl { get; set; }
+
+        private void UpdateHeader(AvaloniaPropertyChangedEventArgs obj)
+        {
+            if (Header == null)
+            {
+                if (obj.NewValue is IHeadered headered)
+                {
+                    if (Header != headered.Header)
+                    {
+                        Header = headered.Header;
+                    }
+                }
+                else
+                {
+                    if (!(obj.NewValue is IControl))
+                    {
+                        Header = obj.NewValue;
+                    }
+                }
+            }
+            else
+            {
+                if (Header == obj.OldValue)
+                {
+                    Header = obj.NewValue;
+                }
+            }          
+        }
+
+        private void UpdateSelectedContent(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (!IsSelected)
+            {
+                return;
+            }
+
+            if (ParentTabControl.SelectedContentTemplate != ContentTemplate)
+            {
+                ParentTabControl.SelectedContentTemplate = ContentTemplate;
+            }
+
+            if (ParentTabControl.SelectedContent != Content)
+            {
+                ParentTabControl.SelectedContent = Content;
+            }
+        }
     }
 }

src/Avalonia.Controls/Templates/TemplateExtensions.cs

@@ -24,12 +24,14 @@ namespace Avalonia.Controls.Templates
         {
             foreach (IControl child in control.GetVisualChildren())
             {
-                if (child.TemplatedParent == templatedParent)
+                var childTemplatedParent = child.TemplatedParent;
+
+                if (childTemplatedParent == templatedParent)
                 {
                     yield return child;
                 }
 
-                if (child.TemplatedParent != null)
+                if (childTemplatedParent != null)
                 {
                     foreach (var descendant in GetTemplateChildren(child, templatedParent))
                     {

src/Avalonia.Controls/Viewbox.cs

@@ -0,0 +1,124 @@
+using System;
+using Avalonia.Media;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Viewbox is used to scale single child.
+    /// </summary>
+    /// <seealso cref="Avalonia.Controls.Decorator" />
+    public class Viewbox : Decorator
+    {
+        /// <summary>
+        /// The stretch property
+        /// </summary>
+        public static AvaloniaProperty<Stretch> StretchProperty =
+                AvaloniaProperty.RegisterDirect<Viewbox, Stretch>(nameof(Stretch),
+                    v => v.Stretch, (c, v) => c.Stretch = v, Stretch.Uniform);
+
+        private Stretch _stretch = Stretch.Uniform;
+
+        /// <summary>
+        /// Gets or sets the stretch mode, 
+        /// which determines how child fits into the available space.
+        /// </summary>
+        /// <value>
+        /// The stretch.
+        /// </value>
+        public Stretch Stretch
+        {
+            get => _stretch;
+            set => SetAndRaise(StretchProperty, ref _stretch, value);
+        }
+
+        static Viewbox()
+        {
+            ClipToBoundsProperty.OverrideDefaultValue<Viewbox>(true);
+            AffectsMeasure<Viewbox>(StretchProperty);
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            var child = Child;
+
+            if (child != null)
+            {
+                child.Measure(Size.Infinity);
+
+                var childSize = child.DesiredSize;
+
+                var scale = GetScale(availableSize, childSize, Stretch);
+
+                return childSize * scale;
+            }
+
+            return new Size();
+        }
+
+        protected override Size ArrangeOverride(Size finalSize)
+        {
+            var child = Child;
+
+            if (child != null)
+            {
+                var childSize = child.DesiredSize;
+                var scale = GetScale(finalSize, childSize, Stretch);
+                var scaleTransform = child.RenderTransform as ScaleTransform;
+
+                if (scaleTransform == null)
+                {
+                    child.RenderTransform = scaleTransform = new ScaleTransform(scale.X, scale.Y);
+                    child.RenderTransformOrigin = RelativePoint.TopLeft;
+                }
+
+                scaleTransform.ScaleX = scale.X;
+                scaleTransform.ScaleY = scale.Y;
+
+                child.Arrange(new Rect(childSize));
+
+                return childSize * scale;
+            }
+
+            return new Size();
+        }
+
+        private static Vector GetScale(Size availableSize, Size childSize, Stretch stretch)
+        {
+            double scaleX = 1.0;
+            double scaleY = 1.0;
+
+            bool validWidth = !double.IsPositiveInfinity(availableSize.Width);
+            bool validHeight = !double.IsPositiveInfinity(availableSize.Height);
+
+            if (stretch != Stretch.None && (validWidth || validHeight))
+            {
+                scaleX = childSize.Width <= 0.0 ? 0.0 : availableSize.Width / childSize.Width;
+                scaleY = childSize.Height <= 0.0 ? 0.0 : availableSize.Height / childSize.Height;
+
+                if (!validWidth)
+                {
+                    scaleX = scaleY;
+                }
+                else if (!validHeight)
+                {
+                    scaleY = scaleX;
+                }
+                else
+                {
+                    switch (stretch)
+                    {
+                        case Stretch.Uniform:
+                            scaleX = scaleY = Math.Min(scaleX, scaleY);
+                            break;
+
+                        case Stretch.UniformToFill:
+                            scaleX = scaleY = Math.Max(scaleX, scaleY);
+                            break;
+                    }
+                }
+            }
+
+            return new Vector(scaleX, scaleY);
+        }
+    }
+}

src/Avalonia.Styling/StyledElement.cs

@@ -49,8 +49,11 @@ namespace Avalonia
         /// <summary>
         /// Defines the <see cref="TemplatedParent"/> property.
         /// </summary>
-        public static readonly StyledProperty<ITemplatedControl> TemplatedParentProperty =
+        public static readonly DirectProperty<StyledElement, ITemplatedControl> TemplatedParentProperty =
-            AvaloniaProperty.Register<StyledElement, ITemplatedControl>(nameof(TemplatedParent), inherits: true);
+            AvaloniaProperty.RegisterDirect<StyledElement, ITemplatedControl>(
+                nameof(TemplatedParent),
+                o => o.TemplatedParent,
+                (o ,v) => o.TemplatedParent = v);
 
         private int _initCount;
         private string _name;
@@ -62,6 +65,7 @@ namespace Avalonia
         private Styles _styles;
         private bool _styled;
         private Subject<IStyleable> _styleDetach = new Subject<IStyleable>();
+        private ITemplatedControl _templatedParent;
         private bool _dataContextUpdating;
 
         /// <summary>
@@ -269,8 +273,8 @@ namespace Avalonia
         /// </summary>
         public ITemplatedControl TemplatedParent
         {
-            get { return GetValue(TemplatedParentProperty); }
+            get => _templatedParent;
-            internal set { SetValue(TemplatedParentProperty, value); }
+            internal set => SetAndRaise(TemplatedParentProperty, ref _templatedParent, value);
         }
 
         /// <summary>

src/Avalonia.Themes.Default/Accents/BaseDark.xaml

@@ -52,5 +52,7 @@
         <sys:Double x:Key="FontSizeSmall">10</sys:Double>
         <sys:Double x:Key="FontSizeNormal">12</sys:Double>
         <sys:Double x:Key="FontSizeLarge">16</sys:Double>
+
+        <sys:Double x:Key="ScrollBarThickness">10</sys:Double>
     </Style.Resources>
 </Style>

src/Avalonia.Themes.Default/Accents/BaseLight.xaml

@@ -52,5 +52,7 @@
         <sys:Double x:Key="FontSizeSmall">10</sys:Double>
         <sys:Double x:Key="FontSizeNormal">12</sys:Double>
         <sys:Double x:Key="FontSizeLarge">16</sys:Double>
+
+        <sys:Double x:Key="ScrollBarThickness">10</sys:Double>
     </Style.Resources>
 </Style>

src/Avalonia.Themes.Default/DefaultTheme.xaml

@@ -12,7 +12,6 @@
   <StyleInclude Source="resm:Avalonia.Themes.Default.DropDownItem.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.GridSplitter.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.ItemsControl.xaml?assembly=Avalonia.Themes.Default"/>
-  <StyleInclude Source="resm:Avalonia.Themes.Default.LayoutTransformControl.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.ListBox.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.ListBoxItem.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.Menu.xaml?assembly=Avalonia.Themes.Default"/>
@@ -30,6 +29,7 @@
   <StyleInclude Source="resm:Avalonia.Themes.Default.TabStripItem.xaml?assembly=Avalonia.Themes.Default"/>
   <!-- TabControl needs to come after TabStrip as it redefines the inner TabStrip.ItemsPanel-->
   <StyleInclude Source="resm:Avalonia.Themes.Default.TabControl.xaml?assembly=Avalonia.Themes.Default"/>
+  <StyleInclude Source="resm:Avalonia.Themes.Default.TabItem.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.TextBox.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.ToggleButton.xaml?assembly=Avalonia.Themes.Default"/>
   <StyleInclude Source="resm:Avalonia.Themes.Default.Expander.xaml?assembly=Avalonia.Themes.Default"/>

src/Avalonia.Themes.Default/DropDown.xaml

@@ -35,15 +35,21 @@
                    MinWidth="{Binding Bounds.Width, RelativeSource={RelativeSource TemplatedParent}}"
                    MaxHeight="{TemplateBinding MaxDropDownHeight}"
                    PlacementTarget="{TemplateBinding}"
+                   ObeyScreenEdges="True"
                    StaysOpen="False">
               <Border BorderBrush="{DynamicResource ThemeBorderMidBrush}"
                       BorderThickness="1">
-                <ScrollViewer>
+                  <AdornerDecorator Margin="-1 -1 0 0">
-                  <ItemsPresenter Name="PART_ItemsPresenter"
+                      <ScrollViewer>
-                                  Items="{TemplateBinding Items}"
+                          <ItemsPresenter Name="PART_ItemsPresenter"
-                                  ItemTemplate="{TemplateBinding ItemTemplate}"
+                                          Items="{TemplateBinding Items}"
-                                  MemberSelector="{TemplateBinding MemberSelector}"/>
+                                          ItemsPanel="{TemplateBinding ItemsPanel}"
-                </ScrollViewer>
+                                          ItemTemplate="{TemplateBinding ItemTemplate}"
+                                          MemberSelector="{TemplateBinding MemberSelector}"
+                                          VirtualizationMode="{TemplateBinding VirtualizationMode}"
+                                  />
+                      </ScrollViewer>
+                  </AdornerDecorator>
               </Border>
             </Popup>
           </Grid>
@@ -54,4 +60,4 @@
   <Style Selector="DropDown:pointerover /template/ Border#border">
     <Setter Property="BorderBrush" Value="{DynamicResource ThemeBorderHighBrush}"/>
   </Style>
-</Styles>
+</Styles>

src/Avalonia.Themes.Default/DropDownItem.xaml

@@ -18,7 +18,7 @@
       </ControlTemplate>
     </Setter>
   </Style>
-
+    
   <Style Selector="DropDownItem:pointerover /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource ThemeControlHighlightMidBrush}"/>
   </Style>

src/Avalonia.Themes.Default/FocusAdorner.xaml

@@ -3,7 +3,8 @@
     <FocusAdornerTemplate>
       <Rectangle Stroke="Black"
                  StrokeThickness="1"
-                 StrokeDashArray="1,2"/>
+                 StrokeDashArray="1,2"
+                 Margin="1"/>
     </FocusAdornerTemplate>
   </Setter>
-</Style>
+</Style>

src/Avalonia.Themes.Default/LayoutTransformControl.xaml

@@ -1,13 +0,0 @@
-<Style xmlns="https://github.com/avaloniaui" Selector="LayoutTransformControl">
-  <Setter Property="Template">
-    <ControlTemplate>
-      <ContentPresenter Name="PART_ContentPresenter"
-                        Background="{TemplateBinding Background}"
-                        BorderBrush="{TemplateBinding BorderBrush}"
-                        BorderThickness="{TemplateBinding BorderThickness}"
-                        ContentTemplate="{TemplateBinding ContentTemplate}"
-                        Content="{TemplateBinding Content}" 
-                        Padding="{TemplateBinding Padding}"/>
-    </ControlTemplate>
-  </Setter>
-</Style>

src/Avalonia.Themes.Default/ScrollBar.xaml

@@ -3,7 +3,7 @@
         <Setter Property="Template">
             <ControlTemplate>
                 <Border Background="{DynamicResource ThemeControlMidBrush}">
-                    <Grid RowDefinitions="10,*,10">
+                    <Grid RowDefinitions="Auto,*,Auto">
                         <RepeatButton Name="PART_LineUpButton"
                                       Classes="repeat"
                                       Grid.Row="0"
@@ -53,12 +53,11 @@
         </Setter>
     </Style>
     <Style Selector="ScrollBar:horizontal">
-        <Setter Property="Height"
+        <Setter Property="Height" Value="{DynamicResource ScrollBarThickness}" />
-                Value="10" />
         <Setter Property="Template">
             <ControlTemplate>
                 <Border Background="{DynamicResource ThemeControlMidBrush}">
-                    <Grid ColumnDefinitions="10,*,10">
+                    <Grid ColumnDefinitions="Auto,*,Auto">
                         <RepeatButton Name="PART_LineUpButton"
                                       Classes="repeat"
                                       Grid.Row="0"
@@ -108,22 +107,17 @@
         </Setter>
     </Style>
     <Style Selector="ScrollBar:horizontal /template/ Thumb#thumb">
-        <Setter Property="MinWidth"
+        <Setter Property="MinWidth" Value="{DynamicResource ScrollBarThickness}" />
-                Value="10" />
     </Style>
     <Style Selector="ScrollBar:vertical">
-        <Setter Property="Width"
+        <Setter Property="Width" Value="{DynamicResource ScrollBarThickness}" />
-                Value="10" />
     </Style>
     <Style Selector="ScrollBar:vertical /template/ Thumb#thumb">
-        <Setter Property="MinHeight"
+        <Setter Property="MinHeight" Value="{DynamicResource ScrollBarThickness}" />
-                Value="10" />
     </Style>
     <Style Selector="ScrollBar /template/ RepeatButton.repeat">
-        <Setter Property="Padding"
+        <Setter Property="Padding" Value="2" />
-                Value="2" />
+        <Setter Property="BorderThickness" Value="0" />
-        <Setter Property="BorderThickness"
-                Value="0" />
     </Style>
     <Style Selector="ScrollBar /template/ RepeatButton.repeattrack">
         <Setter Property="Template">

src/Avalonia.Themes.Default/TabControl.xaml

@@ -1,50 +1,63 @@
 <Styles xmlns="https://github.com/avaloniaui"  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <Style Selector="TabControl">
+    <Style Selector="TabControl">        
-    <Setter Property="Template">
+        <Setter Property="Template">
-      <ControlTemplate>
+            <ControlTemplate>
-        <Border Background="{TemplateBinding Background}"
+                <Border
-                BorderBrush="{TemplateBinding BorderBrush}"
+                    Margin="{TemplateBinding Margin}"
-                BorderThickness="{TemplateBinding BorderThickness}">
+                    BorderBrush="{TemplateBinding BorderBrush}"
-          <DockPanel>
+                    BorderThickness="{TemplateBinding BorderThickness}"
-            <TabStrip Name="PART_TabStrip"
+                    Background="{TemplateBinding Background}"
-                      MemberSelector="{x:Static TabControl.HeaderSelector}"
+                    HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
-                      Items="{TemplateBinding Items}"
+                    VerticalAlignment="{TemplateBinding VerticalAlignment}">
-                      SelectedIndex="{TemplateBinding SelectedIndex, Mode=TwoWay}"/>
+                    <DockPanel>
-            <Carousel Name="PART_Content"
+                        <ItemsPresenter
-                      MemberSelector="{x:Static TabControl.ContentSelector}"
+                            Name="PART_ItemsPresenter"
-                      Items="{TemplateBinding Items}"
+                            Items="{TemplateBinding Items}"
-                      SelectedIndex="{TemplateBinding SelectedIndex}"
+                            ItemsPanel="{TemplateBinding ItemsPanel}"
-                      PageTransition="{TemplateBinding PageTransition}"
+                            ItemTemplate="{TemplateBinding ItemTemplate}"
-                      Grid.Row="1"/>
+                            MemberSelector="{TemplateBinding MemberSelector}"                     >
-          </DockPanel>
+                        </ItemsPresenter>
-        </Border>
+                        <ContentPresenter
-      </ControlTemplate>
+                            Name="PART_Content"
-    </Setter>
+                            Margin="{TemplateBinding Padding}"
-  </Style>
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-  <Style Selector="TabControl[TabStripPlacement=Top] /template/ TabStrip">
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
-    <Setter Property="DockPanel.Dock" Value="Top"/>
+                            Content="{TemplateBinding SelectedContent}"
-  </Style>
+                            ContentTemplate="{TemplateBinding SelectedContentTemplate}">
-  <Style Selector="TabControl[TabStripPlacement=Bottom] /template/ TabStrip">
+                        </ContentPresenter>
-    <Setter Property="DockPanel.Dock" Value="Bottom"/>
+                    </DockPanel>
-  </Style>
+                </Border>
-  <Style Selector="TabControl[TabStripPlacement=Left] /template/ TabStrip">
+            </ControlTemplate>
-    <Setter Property="DockPanel.Dock" Value="Left"/>
+        </Setter>
-    <Setter Property="ItemsPanel">
+    </Style>
-      <Setter.Value>
+    <Style Selector="TabControl[TabStripPlacement=Top]">
-        <ItemsPanelTemplate>
+        <Setter Property="Padding" Value="0 4 0 0"/>
-          <StackPanel Orientation="Vertical"/>
+    </Style>
-        </ItemsPanelTemplate>
+    <Style Selector="TabControl[TabStripPlacement=Top] /template/ ItemsPresenter#PART_ItemsPresenter">
-      </Setter.Value>
+        <Setter Property="DockPanel.Dock" Value="Top"/>
-    </Setter>
+    </Style>
-  </Style>
+    <Style Selector="TabControl[TabStripPlacement=Bottom] /template/ ItemsPresenter#PART_ItemsPresenter">
-  <Style Selector="TabControl[TabStripPlacement=Right] /template/ TabStrip">
+        <Setter Property="DockPanel.Dock" Value="Bottom"/>
-    <Setter Property="DockPanel.Dock" Value="Right"/>
+    </Style>
-    <Setter Property="ItemsPanel">
+    <Style Selector="TabControl[TabStripPlacement=Bottom]">
-      <Setter.Value>
+        <Setter Property="Padding" Value="0 0 0 4"/>
-        <ItemsPanelTemplate>
+    </Style>
-          <StackPanel Orientation="Vertical"/>
+    <Style Selector="TabControl[TabStripPlacement=Left] /template/ ItemsPresenter#PART_ItemsPresenter">
-        </ItemsPanelTemplate>
+        <Setter Property="DockPanel.Dock" Value="Left"/>
-      </Setter.Value>
+    </Style>
-    </Setter>
+    <Style Selector="TabControl[TabStripPlacement=Left] /template/ ItemsPresenter#PART_ItemsPresenter > WrapPanel">
-  </Style>
+        <Setter Property="Orientation" Value="Vertical"/>
-</Styles>
+    </Style>
+    <Style Selector="TabControl[TabStripPlacement=Left]">
+        <Setter Property="Padding" Value="4 0 0 0"/>
+    </Style>
+    <Style Selector="TabControl[TabStripPlacement=Right] /template/ ItemsPresenter#PART_ItemsPresenter">
+        <Setter Property="DockPanel.Dock" Value="Right"/>
+    </Style>
+    <Style Selector="TabControl[TabStripPlacement=Right] /template/ ItemsPresenter#PART_ItemsPresenter > WrapPanel">
+        <Setter Property="Orientation" Value="Vertical"/>
+    </Style>
+    <Style Selector="TabControl[TabStripPlacement=Right]">
+        <Setter Property="Padding" Value="0 0 0 4"/>
+    </Style>
+</Styles>

src/Avalonia.Themes.Default/TabItem.xaml

@@ -0,0 +1,45 @@
+<Styles xmlns="https://github.com/avaloniaui">
+    <Style Selector="TabItem">
+        <Setter Property="Background" Value="Transparent"/>
+        <Setter Property="FontSize" Value="{DynamicResource FontSizeLarge}"/>
+        <Setter Property="Foreground" Value="{DynamicResource ThemeForegroundLightBrush}"/>
+        <Setter Property="HorizontalContentAlignment" Value="Left"/>
+        <Setter Property="Padding" Value="8"/>
+        <Setter Property="Template">
+            <ControlTemplate>
+                <ContentPresenter
+                    Name="PART_ContentPresenter"
+                    Background="{TemplateBinding Background}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
+                    BorderThickness="{TemplateBinding BorderThickness}"
+                    ContentTemplate="{TemplateBinding HeaderTemplate}"
+                    Content="{TemplateBinding Header}"
+                    HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                    VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                    Margin="{TemplateBinding Margin}"
+                    Padding="{TemplateBinding Padding}"/>
+            </ControlTemplate>
+        </Setter>
+    </Style>
+    <Style Selector="TabItem:disabled">
+        <Setter Property="Opacity" Value="{DynamicResource ThemeDisabledOpacity}"/>
+    </Style>
+    <Style Selector="TabItem:pointerover /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeControlHighlightMidBrush}"/>
+    </Style>
+    <Style Selector="TabItem:selected /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush4}"/>
+    </Style>
+    <Style Selector="TabItem:selected:focus /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush3}"/>
+    </Style>
+    <Style Selector="TabItem:selected:pointerover /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush3}"/>
+    </Style>
+    <Style Selector="TabItem:selected:focus:pointerover /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush2}"/>
+    </Style>
+    <Style Selector="TabItem[TabStripPlacement=Right]">
+        <Setter Property="HorizontalContentAlignment" Value="Right"/>
+    </Style>
+</Styles>

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -37,6 +37,7 @@ namespace Avalonia.Rendering
         private DisplayDirtyRects _dirtyRectsDisplay = new DisplayDirtyRects();
         private IRef<IDrawOperation> _currentDraw;
         private readonly IDeferredRendererLock _lock;
+        private readonly object _sceneLock = new object();
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DeferredRenderer"/> class.
@@ -84,6 +85,7 @@ namespace Avalonia.Rendering
             RenderTarget = renderTarget;
             _sceneBuilder = sceneBuilder ?? new SceneBuilder();
             Layers = new RenderLayers();
+            _lock = new ManagedDeferredRendererLock();
         }
 
         /// <inheritdoc/>
@@ -118,8 +120,13 @@ namespace Avalonia.Rendering
         /// </summary>
         public void Dispose()
         {
-            var scene = Interlocked.Exchange(ref _scene, null);
+            lock (_sceneLock)
-            scene?.Dispose();
+            {
+                var scene = _scene;
+                _scene = null;
+                scene?.Dispose();
+            }
+
             Stop();
 
             Layers.Clear();
@@ -134,7 +141,8 @@ namespace Avalonia.Rendering
                 // When unit testing the renderLoop may be null, so update the scene manually.
                 UpdateScene();
             }
-
+            //It's safe to access _scene here without a lock since
+            //it's only changed from UI thread which we are currently on
             return _scene?.Item.HitTest(p, root, filter) ?? Enumerable.Empty<IVisual>();
         }
 
@@ -172,7 +180,8 @@ namespace Avalonia.Rendering
             }
         }
 
-        bool IRenderLoopTask.NeedsUpdate => _dirty == null || _dirty.Count > 0;
+        bool NeedsUpdate => _dirty == null || _dirty.Count > 0;
+        bool IRenderLoopTask.NeedsUpdate => NeedsUpdate;
 
         void IRenderLoopTask.Update(TimeSpan time) => UpdateScene();
 
@@ -197,79 +206,105 @@ namespace Avalonia.Rendering
 
         internal void UnitTestUpdateScene() => UpdateScene();
 
-        internal void UnitTestRender() => Render(_scene.Item, false);
+        internal void UnitTestRender() => Render(false);
 
         private void Render(bool forceComposite)
         {
             using (var l = _lock.TryLock())
-                if (l != null)
-                    using (var scene = _scene?.Clone())
-                    {
-                        Render(scene?.Item, forceComposite);
-                    }
-        }
-        
-        private void Render(Scene scene, bool forceComposite)
-        {
-            bool renderOverlay = DrawDirtyRects || DrawFps;
-            bool composite = false;
-
-            if (RenderTarget == null)
             {
-                RenderTarget = ((IRenderRoot)_root).CreateRenderTarget();
+                if (l == null)
-            }
+                    return;
 
-            if (renderOverlay)
+                IDrawingContextImpl context = null;
-            {
+                try
-                _dirtyRectsDisplay.Tick();
-            }
-
-            try
-            {
-                if (scene != null && scene.Size != Size.Empty)
                 {
-                    IDrawingContextImpl context = null;
+                    try
-
-                    if (scene.Generation != _lastSceneId)
                     {
-                        context = RenderTarget.CreateDrawingContext(this);
+                        IDrawingContextImpl GetContext()
-                        Layers.Update(scene, context);
+                        {
+                            if (context != null)
+                                return context;
+                            if (RenderTarget == null)
+                                RenderTarget = ((IRenderRoot)_root).CreateRenderTarget();
+                            return context = RenderTarget.CreateDrawingContext(this);
 
-                        RenderToLayers(scene);
+                        }
 
-                        if (DebugFramesPath != null)
+                        var (scene, updated) = UpdateRenderLayersAndConsumeSceneIfNeeded(GetContext);
+                        using (scene)
                         {
-                            SaveDebugFrames(scene.Generation);
+                            var overlay = DrawDirtyRects || DrawFps;
+                            if (DrawDirtyRects)
+                                _dirtyRectsDisplay.Tick();
+                            if (overlay)
+                                RenderOverlay(scene.Item, GetContext());
+                            if (updated || forceComposite || overlay)
+                                RenderComposite(scene.Item, GetContext());
                         }
+                    }
+                    finally
+                    {
+                        context?.Dispose();
+                    }
+                }
+                catch (RenderTargetCorruptedException ex)
+                {
+                    Logging.Logger.Information("Renderer", this, "Render target was corrupted. Exception: {0}", ex);
+                    RenderTarget?.Dispose();
+                    RenderTarget = null;
+                }
+            }
+        }
 
-                        _lastSceneId = scene.Generation;
+        private (IRef<Scene> scene, bool updated) UpdateRenderLayersAndConsumeSceneIfNeeded(Func<IDrawingContextImpl> contextFactory,
+            bool recursiveCall = false)
+        {
+            IRef<Scene> sceneRef;
+            lock (_sceneLock)
+                sceneRef = _scene?.Clone();
+            if (sceneRef == null)
+                return (null, false);
+            using (sceneRef)
+            {
+                var scene = sceneRef.Item;
+                if (scene.Generation != _lastSceneId)
+                {
+                    var context = contextFactory();
+                    Layers.Update(scene, context);
 
-                        composite = true;
+                    RenderToLayers(scene);
-                    }
 
-                    if (renderOverlay)
+                    if (DebugFramesPath != null)
                     {
-                        context = context ?? RenderTarget.CreateDrawingContext(this);
+                        SaveDebugFrames(scene.Generation);
-                        RenderOverlay(scene, context);
-                        RenderComposite(scene, context);
                     }
-                    else if (composite || forceComposite)
+
+                    lock (_sceneLock)
+                        _lastSceneId = scene.Generation;
+
+
+                    // We have consumed the previously available scene, but there might be some dirty 
+                    // rects since the last update. *If* we are on UI thread, we can force immediate scene
+                    // rebuild before rendering anything on-screen
+                    // We are calling the same method recursively here 
+                    if (!recursiveCall && Dispatcher.UIThread.CheckAccess() && NeedsUpdate)
                     {
-                        context = context ?? RenderTarget.CreateDrawingContext(this);
+                        UpdateScene();
-                        RenderComposite(scene, context);
+                        var (rs, _) = UpdateRenderLayersAndConsumeSceneIfNeeded(contextFactory, true);
+                        return (rs, true);
                     }
-
+                    
-                    context?.Dispose();
+                    // Indicate that we have updated the layers
+                    return (sceneRef.Clone(), true);
                 }
+                
+                // Just return scene, layers weren't updated
+                return (sceneRef.Clone(), false);
             }
-            catch (RenderTargetCorruptedException ex)
+            
-            {
-                Logging.Logger.Information("Renderer", this, "Render target was corrupted. Exception: {0}", ex);
-                RenderTarget?.Dispose();
-                RenderTarget = null;
-            }
         }
 
+
         private void Render(IDrawingContextImpl context, VisualNode node, IVisual layer, Rect clipBounds)
         {
             if (layer == null || node.LayerRoot == layer)
@@ -405,6 +440,11 @@ namespace Avalonia.Rendering
         private void UpdateScene()
         {
             Dispatcher.UIThread.VerifyAccess();
+            lock (_sceneLock)
+            {
+                if (_scene?.Item.Generation > _lastSceneId)
+                    return;
+            }
             if (_root.IsVisible)
             {
                 var sceneRef = RefCountable.Create(_scene?.Item.CloneScene() ?? new Scene(_root));
@@ -423,15 +463,23 @@ namespace Avalonia.Rendering
                     }
                 }
 
-                var oldScene = Interlocked.Exchange(ref _scene, sceneRef);
+                lock (_sceneLock)
-                oldScene?.Dispose();
+                {
+                    var oldScene = _scene;
+                    _scene = sceneRef;
+                    oldScene?.Dispose();
+                }
 
                 _dirty.Clear();
             }
             else
             {
-                var oldScene = Interlocked.Exchange(ref _scene, null);
+                lock (_sceneLock)
-                oldScene?.Dispose();
+                {
+                    var oldScene = _scene;
+                    _scene = null;
+                    oldScene?.Dispose();
+                }
             }
         }
 

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/RelativeSourceExtension.cs

@@ -1,13 +1,12 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using System;
 using Avalonia.Data;
+using Portable.Xaml.Markup;
 
 namespace Avalonia.Markup.Xaml.MarkupExtensions
 {
-    using Portable.Xaml.Markup;
-    using System;
-
     public class RelativeSourceExtension : MarkupExtension
     {
         public RelativeSourceExtension()
@@ -24,10 +23,19 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
             return new RelativeSource
             {
                 Mode = Mode,
+                AncestorType = AncestorType,
+                AncestorLevel = AncestorLevel,
+                Tree = Tree,
             };
         }
 
         [ConstructorArgument("mode")]
-        public RelativeSourceMode Mode { get; set; }
+        public RelativeSourceMode Mode { get; set; } = RelativeSourceMode.FindAncestor;
+
+        public Type AncestorType { get; set; }
+
+        public TreeType Tree { get; set; }
+
+        public int AncestorLevel { get; set; } = 1;
     }
 }

src/Shared/PlatformSupport/StandardRuntimePlatform.cs

@@ -89,9 +89,11 @@ namespace Avalonia.Shared.PlatformSupport
 #if DEBUG
                 if (Thread.CurrentThread.ManagedThreadId == GCThread?.ManagedThreadId)
                 {
-                    Console.Error.WriteLine("Native blob disposal from finalizer thread\nBacktrace: "
+                    lock(_lock)
-                                            + Environment.StackTrace
+                        if (!IsDisposed)
-                                            + "\n\nBlob created by " + _backtrace);
+                            Console.Error.WriteLine("Native blob disposal from finalizer thread\nBacktrace: "
+                                                    + Environment.StackTrace
+                                                    + "\n\nBlob created by " + _backtrace);
                 }
 #endif
                 DoDispose();

src/Windows/Avalonia.Win32/FramebufferManager.cs

@@ -5,7 +5,7 @@ using Avalonia.Win32.Interop;
 
 namespace Avalonia.Win32
 {
-    class FramebufferManager : IFramebufferPlatformSurface, IDisposable
+    class FramebufferManager : IFramebufferPlatformSurface
     {
         private readonly IntPtr _hwnd;
         private WindowFramebuffer _fb;
@@ -29,10 +29,5 @@ namespace Avalonia.Win32
             }
             return _fb;
         }
-
-        public void Dispose()
-        {
-            _fb?.Deallocate();
-        }
     }
 }

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -13,6 +13,7 @@ using Avalonia.Input.Raw;
 using Avalonia.OpenGL;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Threading;
 using Avalonia.Win32.Input;
 using Avalonia.Win32.Interop;
 using static Avalonia.Win32.Interop.UnmanagedMethods;
@@ -234,8 +235,6 @@ namespace Avalonia.Win32
 
         public void Dispose()
         {
-            _framebuffer?.Dispose();
-            _framebuffer = null;
             if (_hwnd != IntPtr.Zero)
             {
                 UnmanagedMethods.DestroyWindow(_hwnd);

tests/Avalonia.Controls.UnitTests/LayoutTransformControlTests.cs

@@ -1,6 +1,4 @@
-using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Shapes;
-using Avalonia.Controls.Templates;
 using Avalonia.Media;
 using Xunit;
 
@@ -311,20 +309,10 @@ namespace Avalonia.Controls.UnitTests
         {
             var lt = new LayoutTransformControl()
             {
-                LayoutTransform = transform,
+                LayoutTransform = transform
-                Template = new FuncControlTemplate<LayoutTransformControl>(
-                                p => new ContentPresenter() { Content = p.Content })
             };
 
-            lt.Content = new Rectangle() { Width = width, Height = height };
+            lt.Child = new Rectangle() { Width = width, Height = height };
-
-            lt.ApplyTemplate();
-
-            //we need to force create visual child
-            //so the measure after is correct
-            (lt.Presenter as ContentPresenter).UpdateChild();
-
-            Assert.NotNull(lt.Presenter?.Child);
 
             lt.Measure(Size.Infinity);
             lt.Arrange(new Rect(lt.DesiredSize));
@@ -332,4 +320,4 @@ namespace Avalonia.Controls.UnitTests
             return lt;
         }
     }
-}
+}

tests/Avalonia.Controls.UnitTests/TabControlTests.cs

@@ -22,7 +22,7 @@ namespace Avalonia.Controls.UnitTests
             TabItem selected;
             var target = new TabControl
             {
-                Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                Template = TabControlTemplate(),
                 Items = new[]
                 {
                     (selected = new TabItem
@@ -61,7 +61,7 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new TabControl
             {
-                Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                Template = TabControlTemplate(),
                 Items = items,
             };
 
@@ -94,7 +94,7 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new TabControl
             {
-                Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                Template = TabControlTemplate(),
                 Items = collection,
             };
 
@@ -147,7 +147,7 @@ namespace Avalonia.Controls.UnitTests
                     },
                     Child = new TabControl
                     {
-                        Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                        Template = TabControlTemplate(),
                         Items = collection,
                     }
                 };
@@ -172,7 +172,7 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new TabControl
             {
-                Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                Template = TabControlTemplate(),
                 DataContext = "Base",
                 DataTemplates =
                 {
@@ -182,41 +182,39 @@ namespace Avalonia.Controls.UnitTests
             };
 
             ApplyTemplate(target);
-            var carousel = (Carousel)target.Pages;
 
-            var container = (ContentPresenter)carousel.Presenter.Panel.Children.Single();
+            target.ContentPart.UpdateChild();
-            container.UpdateChild();
+            var dataContext = ((TextBlock)target.ContentPart.Child).DataContext;
-            var dataContext = ((TextBlock)container.Child).DataContext;
             Assert.Equal(items[0], dataContext);
 
             target.SelectedIndex = 1;
-            container = (ContentPresenter)carousel.Presenter.Panel.Children.Single();
+            target.ContentPart.UpdateChild();
-            container.UpdateChild();
+            dataContext = ((Button)target.ContentPart.Child).DataContext;
-            dataContext = ((Button)container.Child).DataContext;
             Assert.Equal(items[1], dataContext);
 
             target.SelectedIndex = 2;
-            dataContext = ((TextBlock)carousel.Presenter.Panel.Children.Single()).DataContext;
+            target.ContentPart.UpdateChild();
+            dataContext = ((TextBlock)target.ContentPart.Child).DataContext;
             Assert.Equal("Base", dataContext);
 
             target.SelectedIndex = 3;
-            container = (ContentPresenter)carousel.Presenter.Panel.Children[0];
+            target.ContentPart.UpdateChild();
-            container.UpdateChild();
+            dataContext = ((TextBlock)target.ContentPart.Child).DataContext;
-            dataContext = ((TextBlock)container.Child).DataContext;
             Assert.Equal("Qux", dataContext);
 
             target.SelectedIndex = 4;
-            dataContext = ((TextBlock)carousel.Presenter.Panel.Children.Single()).DataContext;
+            target.ContentPart.UpdateChild();
+            dataContext = target.ContentPart.DataContext;
             Assert.Equal("Base", dataContext);
         }
 
         /// <summary>
-        /// Non-headered control items should result in TabStripItems with empty content.
+        /// Non-headered control items should result in TabItems with empty header.
         /// </summary>
         /// <remarks>
-        /// If a TabStrip is created with non IHeadered controls as its items, don't try to
+        /// If a TabControl is created with non IHeadered controls as its items, don't try to
-        /// display the control in the TabStripItem: if the TabStrip is part of a TabControl
+        /// display the control in the header: if the control is part of the header then
-        /// then *that* will also try to display the control, resulting in dual-parentage 
+        /// *that* control would also end up in the content region, resulting in dual-parentage 
         /// breakage.
         /// </remarks>
         [Fact]
@@ -230,18 +228,20 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new TabControl
             {
-                Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                Template = TabControlTemplate(),
                 Items = items,
             };
 
             ApplyTemplate(target);
 
-            var result = target.TabStrip.GetLogicalChildren()
+            var logicalChildren = target.ItemsPresenterPart.Panel.GetLogicalChildren();
-                .OfType<TabStripItem>()
+
-                .Select(x => x.Content)
+            var result = logicalChildren
+                .OfType<TabItem>()
+                .Select(x => x.Header)
                 .ToList();
 
-            Assert.Equal(new object[] { string.Empty, string.Empty }, result);
+            Assert.Equal(new object[] { null, null }, result);
         }
 
         [Fact]
@@ -249,7 +249,7 @@ namespace Avalonia.Controls.UnitTests
         {
             TabControl target = new TabControl
             {
-                Template = new FuncControlTemplate<TabControl>(CreateTabControlTemplate),
+                Template = TabControlTemplate(),
                 Items = new[]
                 {
                     new TabItem { Header = "Foo" },
@@ -262,70 +262,61 @@ namespace Avalonia.Controls.UnitTests
 
             target.SelectedIndex = 2;
 
-            var carousel = (Carousel)target.Pages;
+            var page = (TabItem)target.SelectedItem;
-            var page = (TabItem)carousel.SelectedItem;
 
             Assert.Null(page.Content);
         }
 
-        private Control CreateTabControlTemplate(TabControl parent)
+        private IControlTemplate TabControlTemplate()
         {
-            return new StackPanel
+            return new FuncControlTemplate<TabControl>(parent =>
-            {
-                Children =
-                {
-                    new TabStrip
-                    {
-                        Name = "PART_TabStrip",
-                        Template = new FuncControlTemplate<TabStrip>(CreateTabStripTemplate),
-                        MemberSelector = TabControl.HeaderSelector,
-                        [!TabStrip.ItemsProperty] = parent[!TabControl.ItemsProperty],
-                        [!!TabStrip.SelectedIndexProperty] = parent[!!TabControl.SelectedIndexProperty]
-                    },
-                    new Carousel
-                    {
-                        Name = "PART_Content",
-                        Template = new FuncControlTemplate<Carousel>(CreateCarouselTemplate),
-                        MemberSelector = TabControl.ContentSelector,
-                        [!Carousel.ItemsProperty] = parent[!TabControl.ItemsProperty],
-                        [!Carousel.SelectedItemProperty] = parent[!TabControl.SelectedItemProperty],
-                    }
-                }
-            };
-        }
 
-        private Control CreateTabStripTemplate(TabStrip parent)
+                new StackPanel
-        {
+                {
-            return new ItemsPresenter
+                    Children = {
-            {
+                                   new ItemsPresenter
-                Name = "PART_ItemsPresenter",
+                                   {
-                [~ItemsPresenter.ItemsProperty] = parent[~ItemsControl.ItemsProperty],
+                                       Name = "PART_ItemsPresenter",
-                [!CarouselPresenter.MemberSelectorProperty] = parent[!ItemsControl.MemberSelectorProperty],
+                                       [!TabStrip.ItemsProperty] = parent[!TabControl.ItemsProperty],
-            };
+                                       [!TabStrip.ItemTemplateProperty] = parent[!TabControl.ItemTemplateProperty],
+                                   },
+                                   new ContentPresenter
+                                   {
+                                       Name = "PART_Content",
+                                       [!ContentPresenter.ContentProperty] = parent[!TabControl.SelectedContentProperty],
+                                       [!ContentPresenter.ContentTemplateProperty] = parent[!TabControl.SelectedContentTemplateProperty],
+                                   }
+                               }
+                });
         }
 
-        private Control CreateCarouselTemplate(Carousel control)
+        private IControlTemplate TabItemTemplate()
         {
-            return new CarouselPresenter
+            return new FuncControlTemplate<TabItem>(parent =>
-            {
+                new ContentPresenter
-                Name = "PART_ItemsPresenter",
+                {
-                [!CarouselPresenter.ItemsProperty] = control[!ItemsControl.ItemsProperty],
+                    Name = "PART_ContentPresenter",
-                [!CarouselPresenter.ItemsPanelProperty] = control[!ItemsControl.ItemsPanelProperty],
+                    [!ContentPresenter.ContentProperty] = parent[!TabItem.HeaderProperty],
-                [!CarouselPresenter.MemberSelectorProperty] = control[!ItemsControl.MemberSelectorProperty],
+                    [!ContentPresenter.ContentTemplateProperty] = parent[!TabItem.HeaderTemplateProperty]
-                [!CarouselPresenter.SelectedIndexProperty] = control[!SelectingItemsControl.SelectedIndexProperty],
+                });
-                [~CarouselPresenter.PageTransitionProperty] = control[~Carousel.PageTransitionProperty],
-            };
         }
 
         private void ApplyTemplate(TabControl target)
         {
             target.ApplyTemplate();
-            var carousel = (Carousel)target.Pages;
+
-            carousel.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
-            carousel.Presenter.ApplyTemplate();
+
-            var tabStrip = (TabStrip)target.TabStrip;
+            foreach (var tabItem in target.GetLogicalChildren().OfType<TabItem>())
-            tabStrip.ApplyTemplate();
+            {
-            tabStrip.Presenter.ApplyTemplate();
+                tabItem.Template = TabItemTemplate();
+
+                tabItem.ApplyTemplate();
+
+                ((ContentPresenter)tabItem.Presenter).UpdateChild();
+            }
+
+            target.ContentPart.ApplyTemplate();
         }
 
         private class Item

tests/Avalonia.Controls.UnitTests/ViewboxTests.cs

@@ -0,0 +1,105 @@
+using Avalonia.Controls.Shapes;
+using Avalonia.Media;
+using Xunit;
+
+namespace Avalonia.Controls.UnitTests
+{
+    public class ViewboxTests
+    {
+        [Fact]
+        public void Viewbox_Stretch_Uniform_Child()
+        {
+            var target = new Viewbox() { Child = new Rectangle() { Width = 100, Height = 50 } };
+
+            target.Measure(new Size(200, 200));
+            target.Arrange(new Rect(new Point(0, 0), target.DesiredSize));
+
+            Assert.Equal(new Size(200, 100), target.DesiredSize);
+            var scaleTransform = target.Child.RenderTransform as ScaleTransform;
+
+            Assert.NotNull(scaleTransform);
+            Assert.Equal(2.0, scaleTransform.ScaleX);
+            Assert.Equal(2.0, scaleTransform.ScaleY);
+        }
+
+        [Fact]
+        public void Viewbox_Stretch_None_Child()
+        {
+            var target = new Viewbox() { Stretch = Stretch.None, Child = new Rectangle() { Width = 100, Height = 50 } };
+
+            target.Measure(new Size(200, 200));
+            target.Arrange(new Rect(new Point(0, 0), target.DesiredSize));
+
+            Assert.Equal(new Size(100, 50), target.DesiredSize);
+            var scaleTransform = target.Child.RenderTransform as ScaleTransform;
+
+            Assert.NotNull(scaleTransform);
+            Assert.Equal(1.0, scaleTransform.ScaleX);
+            Assert.Equal(1.0, scaleTransform.ScaleY);
+        }
+
+        [Fact]
+        public void Viewbox_Stretch_Fill_Child()
+        {
+            var target = new Viewbox() { Stretch = Stretch.Fill, Child = new Rectangle() { Width = 100, Height = 50 } };
+
+            target.Measure(new Size(200, 200));
+            target.Arrange(new Rect(new Point(0, 0), target.DesiredSize));
+
+            Assert.Equal(new Size(200, 200), target.DesiredSize);
+            var scaleTransform = target.Child.RenderTransform as ScaleTransform;
+
+            Assert.NotNull(scaleTransform);
+            Assert.Equal(2.0, scaleTransform.ScaleX);
+            Assert.Equal(4.0, scaleTransform.ScaleY);
+        }
+
+        [Fact]
+        public void Viewbox_Stretch_UniformToFill_Child()
+        {
+            var target = new Viewbox() { Stretch = Stretch.UniformToFill, Child = new Rectangle() { Width = 100, Height = 50 } };
+
+            target.Measure(new Size(200, 200));
+            target.Arrange(new Rect(new Point(0, 0), target.DesiredSize));
+
+            Assert.Equal(new Size(200, 200), target.DesiredSize);
+            var scaleTransform = target.Child.RenderTransform as ScaleTransform;
+
+            Assert.NotNull(scaleTransform);
+            Assert.Equal(4.0, scaleTransform.ScaleX);
+            Assert.Equal(4.0, scaleTransform.ScaleY);
+        }
+
+        [Fact]
+        public void Viewbox_Stretch_Uniform_Child_With_Unrestricted_Width()
+        {
+            var target = new Viewbox() { Child = new Rectangle() { Width = 100, Height = 50 } };
+
+            target.Measure(new Size(double.PositiveInfinity, 200));
+            target.Arrange(new Rect(new Point(0, 0), target.DesiredSize));
+
+            Assert.Equal(new Size(400, 200), target.DesiredSize);
+            var scaleTransform = target.Child.RenderTransform as ScaleTransform;
+
+            Assert.NotNull(scaleTransform);
+            Assert.Equal(4.0, scaleTransform.ScaleX);
+            Assert.Equal(4.0, scaleTransform.ScaleY);
+        }
+
+        [Fact]
+        public void Viewbox_Stretch_Uniform_Child_With_Unrestricted_Height()
+        {
+            var target = new Viewbox() { Child = new Rectangle() { Width = 100, Height = 50 } };
+
+            target.Measure(new Size(200, double.PositiveInfinity));
+            target.Arrange(new Rect(new Point(0, 0), target.DesiredSize));
+
+            Assert.Equal(new Size(200, 100), target.DesiredSize);
+            var scaleTransform = target.Child.RenderTransform as ScaleTransform;
+
+            Assert.NotNull(scaleTransform);
+            Assert.Equal(2.0, scaleTransform.ScaleX);
+            Assert.Equal(2.0, scaleTransform.ScaleY);
+        }
+    }
+}

tests/Avalonia.Layout.UnitTests/FullLayoutTests.cs

@@ -99,6 +99,8 @@ namespace Avalonia.Layout.UnitTests
                     }
                 };
 
+                window.Resources["ScrollBarThickness"] = 10.0;
+
                 window.Show();
                 window.LayoutManager.ExecuteInitialLayoutPass(window);
 

tests/Avalonia.Markup.UnitTests/Data/BindingTests_RelativeSource.cs

@@ -1,9 +1,13 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using System;
+using System.Collections.Generic;
+using System.Reactive.Subjects;
 using Avalonia.Controls;
 using Avalonia.Data;
-using Avalonia.Markup.Data;
+using Avalonia.Data.Core;
+using Avalonia.Markup.Parsers;
 using Avalonia.UnitTests;
 using Xunit;
 
@@ -162,5 +166,99 @@ namespace Avalonia.Markup.UnitTests.Data
             decorator2.Child = target;
             Assert.Equal("decorator2", target.Text);
         }
+
+        [Fact]
+        public void Should_Update_When_Detached_And_Attached_To_Visual_Tree_With_BindingPath()
+        {
+            TextBlock target;
+            Decorator decorator1;
+            Decorator decorator2;
+
+            var viewModel = new { Value = "Foo" };
+
+            var root1 = new TestRoot
+            {
+                Child = decorator1 = new Decorator
+                {
+                    Name = "decorator1",
+                    Child = target = new TextBlock(),
+                },
+                DataContext = viewModel
+            };
+
+            var root2 = new TestRoot
+            {
+                Child = decorator2 = new Decorator
+                {
+                    Name = "decorator2",
+                },
+                DataContext = viewModel
+            };
+
+            var binding = new Binding
+            {
+                Path = "DataContext.Value",
+                RelativeSource = new RelativeSource
+                {
+                    AncestorType = typeof(Decorator),
+                }
+            };
+
+            target.Bind(TextBox.TextProperty, binding);
+            Assert.Equal("Foo", target.Text);
+
+            decorator1.Child = null;
+            Assert.Null(target.Text);
+
+            decorator2.Child = target;
+            Assert.Equal("Foo", target.Text);
+        }
+
+        [Fact]
+        public void Should_Update_When_Detached_And_Attached_To_Visual_Tree_With_ComplexBindingPath()
+        {
+            TextBlock target;
+            Decorator decorator1;
+            Decorator decorator2;
+
+            var vm = new { Foo = new  { Value = "Foo" } };
+
+            var root1 = new TestRoot
+            {
+                Child = decorator1 = new Decorator
+                {
+                    Name = "decorator1",
+                    Child = target = new TextBlock(),
+                },
+                DataContext = vm
+            };
+
+            var root2 = new TestRoot
+            {
+                Child = decorator2 = new Decorator
+                {
+                    Name = "decorator2",
+                },
+                DataContext = vm
+            };
+
+            var binding = new Binding
+            {
+                Path = "DataContext.Foo.Value",
+                RelativeSource = new RelativeSource
+                {
+                    AncestorType = typeof(Decorator),
+                }
+            };
+
+            target.Bind(TextBox.TextProperty, binding);
+            Assert.Equal("Foo", target.Text);
+
+            decorator1.Child = null;
+            Assert.Null(target.Text);
+
+            decorator2.Child = target;
+            Assert.Equal("Foo", target.Text);
+        }
     }
 }

tests/Avalonia.Markup.UnitTests/Parsers/ExpressionObserverBuilderTests_Property.cs

@@ -1,10 +1,10 @@
-using Avalonia.Data;
+using System;
-using Avalonia.Markup.Parsers;
-using System;
 using System.Collections.Generic;
 using System.Reactive.Linq;
-using System.Text;
+using System.Reactive.Subjects;
 using System.Threading.Tasks;
+using Avalonia.Data;
+using Avalonia.Markup.Parsers;
 using Xunit;
 
 namespace Avalonia.Markup.UnitTests.Parsers
@@ -38,5 +38,55 @@ namespace Avalonia.Markup.UnitTests.Parsers
 
             GC.KeepAlive(data);
         }
+
+        [Fact]
+        public void Should_Update_Value_After_Root_Changes()
+        {
+            var root = new { DataContext = new { Value = "Foo" } };
+            var subject = new Subject<object>();
+            var obs = ExpressionObserverBuilder.Build(subject, "DataContext.Value");
+
+            var values = new List<object>();
+            obs.Subscribe(v => values.Add(v));
+
+            subject.OnNext(root);
+            subject.OnNext(null);
+            subject.OnNext(root);
+
+            Assert.Equal("Foo", values[0]);
+
+            Assert.IsType<BindingNotification>(values[1]);
+            var bn = values[1] as BindingNotification;
+            Assert.Equal(AvaloniaProperty.UnsetValue, bn.Value);
+            Assert.Equal(BindingErrorType.Error, bn.ErrorType);
+
+            Assert.Equal(3, values.Count);
+            Assert.Equal("Foo", values[2]);
+        }
+
+        [Fact]
+        public void Should_Update_Value_After_Root_Changes_With_ComplexPath()
+        {
+            var root = new { DataContext = new { Foo = new { Value = "Foo" } } };
+            var subject = new Subject<object>();
+            var obs = ExpressionObserverBuilder.Build(subject, "DataContext.Foo.Value");
+
+            var values = new List<object>();
+            obs.Subscribe(v => values.Add(v));
+
+            subject.OnNext(root);
+            subject.OnNext(null);
+            subject.OnNext(root);
+
+            Assert.Equal("Foo", values[0]);
+
+            Assert.IsType<BindingNotification>(values[1]);
+            var bn = values[1] as BindingNotification;
+            Assert.Equal(AvaloniaProperty.UnsetValue, bn.Value);
+            Assert.Equal(BindingErrorType.Error, bn.ErrorType);
+
+            Assert.Equal(3, values.Count);
+            Assert.Equal("Foo", values[2]);
+        }
     }
 }

tests/Avalonia.Visuals.UnitTests/Rendering/DeferredRendererTests_HitTesting.cs

@@ -405,7 +405,8 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                 root.Renderer = new DeferredRenderer(root, null);
                 root.Measure(Size.Infinity);
                 root.Arrange(new Rect(container.DesiredSize));
-
+                
+                root.Renderer.Paint(Rect.Empty);
                 var result = root.Renderer.HitTest(new Point(50, 150), root, null).First();
 
                 Assert.Equal(item1, result);
@@ -421,6 +422,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                 container.InvalidateArrange();
                 container.Arrange(new Rect(container.DesiredSize));
 
+                root.Renderer.Paint(Rect.Empty);
                 result = root.Renderer.HitTest(new Point(50, 150), root, null).First();
                 Assert.Equal(item2, result);