Merge branch 'master' into fixes/fluent-fix-checkbox-foreground

samples/ControlCatalog/Pages/DataGridPage.xaml

@@ -11,12 +11,17 @@
       <Setter Property="Background" Value="{Binding Path=GDP, Mode=OneWay, Converter={StaticResource GDPConverter}}" />
     </Style>
   </UserControl.Styles>
-  <Grid RowDefinitions="Auto,*">
+  <Grid RowDefinitions="Auto,Auto,*">
     <StackPanel Orientation="Vertical" Spacing="4" Grid.Row="0">
       <TextBlock Classes="h1">DataGrid</TextBlock>
       <TextBlock Classes="h2">A control for displaying and interacting with a data source.</TextBlock>
     </StackPanel>
-    <TabControl Grid.Row="1">
+    <StackPanel Grid.Row="1" Spacing="4" Orientation="Horizontal" IsVisible="{Binding #EditableTab.IsSelected}">
+      <TextBlock Text="FontSize:" VerticalAlignment="Center"/>
+      <Slider x:Name="FontSizeSlider" Minimum="5" Maximum="30" Value="14" Width="100" VerticalAlignment="Center" />
+      <CheckBox x:Name="IsThreeStateCheckBox" IsChecked="False" Content="IsThreeState"/>
+    </StackPanel>
+    <TabControl Grid.Row="2">
       <TabItem Header="DataGrid">
         <DataGrid Name="dataGrid1" Margin="12" CanUserResizeColumns="True" CanUserReorderColumns="True" CanUserSortColumns="True" HeadersVisibility="All">
           <DataGrid.Columns>
@@ -39,13 +44,13 @@
           </DataGrid.Columns>
         </DataGrid>
       </TabItem>
-      <TabItem Header="Editable">
+      <TabItem x:Name="EditableTab" Header="Editable">
         <Grid RowDefinitions="*,Auto">
           <DataGrid Name="dataGridEdit" Margin="12" Grid.Row="0">
             <DataGrid.Columns>
-              <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="2*" />
+              <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
-              <DataGridTextColumn Header="Last" Binding="{Binding LastName}" Width="2*" />
+              <DataGridTextColumn Header="Last" Binding="{Binding LastName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
-              <DataGridCheckBoxColumn Header="Is Banned" Binding="{Binding IsBanned}" Width="*" />
+              <DataGridCheckBoxColumn Header="Is Banned" Binding="{Binding IsBanned}" Width="*" IsThreeState="{Binding #IsThreeStateCheckBox.IsChecked, Mode=OneWay}" />
             </DataGrid.Columns>
           </DataGrid>
           <Button Grid.Row="1" Name="btnAdd" Margin="12,0,12,12" Content="Add" HorizontalAlignment="Right" />

src/Avalonia.Animation/KeySplineTypeConverter.cs

@@ -19,7 +19,7 @@ namespace Avalonia.Animation
 
         public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
         {
-            return KeySpline.Parse((string)value, culture);
+            return KeySpline.Parse((string)value, CultureInfo.InvariantCulture);
         }
     }
 }

src/Avalonia.Base/Data/Core/Plugins/DataAnnotationsValidationPlugin.cs

@@ -63,12 +63,12 @@ namespace Avalonia.Data.Core.Plugins
             {
                 if (errors.Count == 1)
                 {
-                    return new ValidationException(errors[0].ErrorMessage);
+                    return new DataValidationException(errors[0].ErrorMessage);
                 }
                 else
                 {
                     return new AggregateException(
-                        errors.Select(x => new ValidationException(x.ErrorMessage)));
+                        errors.Select(x => new DataValidationException(x.ErrorMessage)));
                 }
             }
         }

src/Avalonia.Controls.DataGrid/ApiCompatBaseline.txt

@@ -0,0 +1,5 @@
+Compat issues with assembly Avalonia.Controls.DataGrid:
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.String> Avalonia.StyledProperty<System.String> Avalonia.Controls.DataGridTextColumn.FontFamilyProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.String Avalonia.Controls.DataGridTextColumn.FontFamily.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.DataGridTextColumn.FontFamily.set(System.String)' does not exist in the implementation but it does exist in the contract.
+Total Issues: 3

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -31,7 +31,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Displays data in a customizable grid.
     /// </summary>
-    [PseudoClasses(":invalid")]
+    [PseudoClasses(":invalid", ":empty-rows", ":empty-columns")]
     public partial class DataGrid : TemplatedControl
     {
         private const string DATAGRID_elementRowsPresenterName = "PART_RowsPresenter";
@@ -711,6 +711,7 @@ namespace Avalonia.Controls
 
             DisplayData = new DataGridDisplayData(this);
             ColumnsInternal = CreateColumnsInstance();
+            ColumnsInternal.CollectionChanged += ColumnsInternal_CollectionChanged;
 
             RowHeightEstimate = DATAGRID_defaultRowHeight;
             RowDetailsHeightEstimate = 0;
@@ -727,6 +728,8 @@ namespace Avalonia.Controls
             CurrentCellCoordinates = new DataGridCellCoordinates(-1, -1);
 
             RowGroupHeaderHeightEstimate = DATAGRID_defaultRowHeight;
+
+            UpdatePseudoClasses();
         }
 
         private void SetValueNoCallback<T>(AvaloniaProperty<T> property, T value, BindingPriority priority = BindingPriority.LocalValue)
@@ -851,9 +854,27 @@ namespace Avalonia.Controls
                 // can be set when the DataGrid is not part of the visual tree
                 _measured = false;
                 InvalidateMeasure();
+
+                UpdatePseudoClasses();
             }
         }
 
+        private void ColumnsInternal_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            if (e.Action == NotifyCollectionChangedAction.Add
+                || e.Action == NotifyCollectionChangedAction.Remove
+                || e.Action == NotifyCollectionChangedAction.Reset)
+            {
+                UpdatePseudoClasses();
+            }
+        }
+
+        internal void UpdatePseudoClasses()
+        {
+            PseudoClasses.Set(":empty-columns", !ColumnsInternal.GetVisibleColumns().Any());
+            PseudoClasses.Set(":empty-rows", !DataConnection.Any());
+        }
+
         private void OnSelectedIndexChanged(AvaloniaPropertyChangedEventArgs e)
         {
             if (!_areHandlersSuspended)
@@ -1348,7 +1369,6 @@ namespace Avalonia.Controls
         internal DataGridColumnCollection ColumnsInternal
         {
             get;
-            private set;
         }
 
         internal int AnchorSlot

src/Avalonia.Controls.DataGrid/DataGridCheckBoxColumn.cs

@@ -17,9 +17,7 @@ namespace Avalonia.Controls
     /// </summary>
     public class DataGridCheckBoxColumn : DataGridBoundColumn
     {
-
         private bool _beganEditWithKeyboard;
-        private bool _isThreeState;
         private CheckBox _currentCheckBox;
         private DataGrid _owningGrid;
 
@@ -31,6 +29,12 @@ namespace Avalonia.Controls
             BindingTarget = CheckBox.IsCheckedProperty;
         }
 
+        /// <summary>
+        /// Defines the <see cref="IsThreeState"/> property.
+        /// </summary>
+        public static StyledProperty<bool> IsThreeStateProperty =
+            CheckBox.IsThreeStateProperty.AddOwner<DataGridCheckBoxColumn>();
+
         /// <summary>
         /// Gets or sets a value that indicates whether the hosted <see cref="T:System.Windows.Controls.CheckBox" /> controls allow three states or two. 
         /// </summary>
@@ -39,17 +43,17 @@ namespace Avalonia.Controls
         /// </returns>
         public bool IsThreeState
         {
-            get
+            get => GetValue(IsThreeStateProperty);
-            {
+            set => SetValue(IsThreeStateProperty, value);
-                return _isThreeState;
+        }
-            }
+
-            set
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == IsThreeStateProperty)
             {
-                if (_isThreeState != value)
+                NotifyPropertyChanged(change.Property.Name);
-                {
-                    _isThreeState = value;
-                    NotifyPropertyChanged(nameof(IsThreeState));
-                }
             }
         }
 
@@ -203,9 +207,9 @@ namespace Avalonia.Controls
             {
                 throw new ArgumentNullException("element");
             }
-            if(element is CheckBox checkBox)
+            if (element is CheckBox checkBox)
             {
-                checkBox.IsThreeState = IsThreeState;
+                DataGridHelper.SyncColumnProperty(this, checkBox, IsThreeStateProperty);
             }
             else
             {
@@ -229,7 +233,7 @@ namespace Avalonia.Controls
         {
             checkBox.HorizontalAlignment = HorizontalAlignment.Center;
             checkBox.VerticalAlignment = VerticalAlignment.Center;
-            checkBox.IsThreeState = IsThreeState;
+            DataGridHelper.SyncColumnProperty(this, checkBox, IsThreeStateProperty);
         }
 
         private bool EnsureOwningGrid()

src/Avalonia.Controls.DataGrid/DataGridDataConnection.cs

@@ -77,24 +77,7 @@ namespace Avalonia.Controls
             private set;
         }
 
-        public int Count
+        public int Count => GetCount(true);
-        {
-            get
-            {
-                IList list = List;
-                if (list != null)
-                {
-                    return list.Count;
-                }
-
-                if(DataSource is DataGridCollectionView cv)
-                {
-                    return cv.Count;
-                }
-
-                return DataSource?.Cast<object>().Count() ?? 0;
-            }
-        }
 
         public bool DataIsPrimitive
         {
@@ -210,6 +193,24 @@ namespace Avalonia.Controls
             }
         }
 
+        internal bool Any()
+        {
+            return GetCount(false) > 0;
+        }
+
+        /// <param name="allowSlow">When "allowSlow" is false, method will not use Linq.Count() method and will return 0 or 1 instead.</param>
+        private int GetCount(bool allowSlow)
+        {
+            return DataSource switch
+            {
+                ICollection collection => collection.Count,
+                DataGridCollectionView cv => cv.Count,
+                IEnumerable enumerable when allowSlow => enumerable.Cast<object>().Count(),
+                IEnumerable enumerable when !allowSlow => enumerable.Cast<object>().Any() ? 1 : 0,
+                _ => 0
+            };
+        }
+
         /// <summary>
         /// Puts the entity into editing mode if possible
         /// </summary>
@@ -675,6 +676,8 @@ namespace Avalonia.Controls
                     }
                     break;
             }
+
+            _owner.UpdatePseudoClasses();
         }
 
         private void UpdateDataProperties()

src/Avalonia.Controls.DataGrid/DataGridTextColumn.cs

@@ -20,11 +20,6 @@ namespace Avalonia.Controls
     {
         private const string DATAGRID_TextColumnCellTextBlockMarginKey = "DataGridTextColumnCellTextBlockMargin";
 
-        private double? _fontSize;
-        private FontStyle? _fontStyle;
-        private FontWeight? _fontWeight;
-        private IBrush _foreground;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="T:Avalonia.Controls.DataGridTextColumn" /> class.
         /// </summary>
@@ -36,18 +31,24 @@ namespace Avalonia.Controls
         /// <summary>
         /// Identifies the FontFamily dependency property.
         /// </summary>
-        public static readonly StyledProperty<string> FontFamilyProperty =
+        public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
-            AvaloniaProperty.Register<DataGridTextColumn, string>(nameof(FontFamily));
+            TextBlock.FontFamilyProperty.AddOwner<DataGridTextColumn>();
 
         /// <summary>
         /// Gets or sets the font name.
         /// </summary>
-        public string FontFamily
+        public FontFamily FontFamily
         {
-            get { return GetValue(FontFamilyProperty); }
+            get => GetValue(FontFamilyProperty);
-            set { SetValue(FontFamilyProperty, value); }
+            set => SetValue(FontFamilyProperty, value);
         }
 
+        /// <summary>
+        /// Identifies the FontSize dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<double> FontSizeProperty =
+            TextBlock.FontSizeProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets the font size.
         /// </summary>
@@ -55,74 +56,66 @@ namespace Avalonia.Controls
         [DefaultValue(double.NaN)]
         public double FontSize
         {
-            get
+            get => GetValue(FontSizeProperty);
-            {
+            set => SetValue(FontSizeProperty, value);
-                return _fontSize ?? Double.NaN;
-            }
-            set
-            {
-                if (_fontSize != value)
-                {
-                    _fontSize = value;
-                    NotifyPropertyChanged(nameof(FontSize));
-                }
-            }
         }
 
+        /// <summary>
+        /// Identifies the FontStyle dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<FontStyle> FontStyleProperty =
+            TextBlock.FontStyleProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets the font style.
         /// </summary>
         public FontStyle FontStyle
         {
-            get
+            get => GetValue(FontStyleProperty);
-            {
+            set => SetValue(FontStyleProperty, value);
-                return _fontStyle ?? FontStyle.Normal;
-            }
-            set
-            {
-                if (_fontStyle != value)
-                {
-                    _fontStyle = value;
-                    NotifyPropertyChanged(nameof(FontStyle));
-                }
-            }
         }
 
+        /// <summary>
+        /// Identifies the FontWeight dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<FontWeight> FontWeightProperty =
+            TextBlock.FontWeightProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets the font weight or thickness.
         /// </summary>
         public FontWeight FontWeight
         {
-            get
+            get => GetValue(FontWeightProperty);
-            {
+            set => SetValue(FontWeightProperty, value);
-                return _fontWeight ?? FontWeight.Normal;
-            }
-            set
-            {
-                if (_fontWeight != value)
-                {
-                    _fontWeight = value;
-                    NotifyPropertyChanged(nameof(FontWeight));
-                }
-            }
         }
 
+        /// <summary>
+        /// Identifies the Foreground dependency property.
+        /// </summary>
+        public static readonly AttachedProperty<IBrush> ForegroundProperty =
+            TextBlock.ForegroundProperty.AddOwner<DataGridTextColumn>();
+
         /// <summary>
         /// Gets or sets a brush that describes the foreground of the column cells.
         /// </summary>
         public IBrush Foreground
         {
-            get
+            get => GetValue(ForegroundProperty);
-            {
+            set => SetValue(ForegroundProperty, value);
-                return _foreground;
+        }
-            }
+
-            set
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == FontFamilyProperty
+                || change.Property == FontSizeProperty
+                || change.Property == FontStyleProperty
+                || change.Property == FontWeightProperty
+                || change.Property == ForegroundProperty)
             {
-                if (_foreground != value)
+                NotifyPropertyChanged(change.Property.Name);
-                {
-                    _foreground = value;
-                    NotifyPropertyChanged(nameof(Foreground));
-                }
             }
         }
 
@@ -154,26 +147,7 @@ namespace Avalonia.Controls
                 Background = new SolidColorBrush(Colors.Transparent)
             };
 
-            if (IsSet(FontFamilyProperty))
+            SyncProperties(textBox);
-            {
-                textBox.FontFamily = FontFamily;
-            }
-            if (_fontSize.HasValue)
-            {
-                textBox.FontSize = _fontSize.Value;
-            }
-            if (_fontStyle.HasValue)
-            {
-                textBox.FontStyle = _fontStyle.Value;
-            }
-            if (_fontWeight.HasValue)
-            {
-                textBox.FontWeight = _fontWeight.Value;
-            }
-            if (_foreground != null)
-            {
-                textBox.Foreground = _foreground;
-            }
 
             return textBox;
         }
@@ -192,26 +166,8 @@ namespace Avalonia.Controls
                 VerticalAlignment = VerticalAlignment.Center
             };
 
-            if (IsSet(FontFamilyProperty))
+            SyncProperties(textBlockElement);
-            {
+
-                textBlockElement.FontFamily = FontFamily;
-            }
-            if (_fontSize.HasValue)
-            {
-                textBlockElement.FontSize = _fontSize.Value;
-            }
-            if (_fontStyle.HasValue)
-            {
-                textBlockElement.FontStyle = _fontStyle.Value;
-            }
-            if (_fontWeight.HasValue)
-            {
-                textBlockElement.FontWeight = _fontWeight.Value;
-            }
-            if (_foreground != null)
-            {
-                textBlockElement.Foreground = _foreground;
-            }
             if (Binding != null)
             {
                 textBlockElement.Bind(TextBlock.TextProperty, Binding);
@@ -261,99 +217,42 @@ namespace Avalonia.Controls
                 throw new ArgumentNullException("element");
             }
 
-            if(element is TextBox textBox)
+            if (element is AvaloniaObject content)
             {
                 if (propertyName == nameof(FontFamily))
                 {
-                    textBox.FontFamily = FontFamily;
+                    DataGridHelper.SyncColumnProperty(this, content, FontFamilyProperty);
                 }
                 else if (propertyName == nameof(FontSize))
                 {
-                    SetTextFontSize(textBox, TextBox.FontSizeProperty);
+                    DataGridHelper.SyncColumnProperty(this, content, FontSizeProperty);
                 }
                 else if (propertyName == nameof(FontStyle))
                 {
-                    textBox.FontStyle = FontStyle;
+                    DataGridHelper.SyncColumnProperty(this, content, FontStyleProperty);
                 }
                 else if (propertyName == nameof(FontWeight))
                 {
-                    textBox.FontWeight = FontWeight;
+                    DataGridHelper.SyncColumnProperty(this, content, FontWeightProperty);
                 }
                 else if (propertyName == nameof(Foreground))
                 {
-                    textBox.Foreground = Foreground;
+                    DataGridHelper.SyncColumnProperty(this, content, ForegroundProperty);
-                }
-                else
-                {
-                    if (FontFamily != null)
-                    {
-                        textBox.FontFamily = FontFamily;
-                    }
-                    SetTextFontSize(textBox, TextBox.FontSizeProperty);
-                    textBox.FontStyle = FontStyle;
-                    textBox.FontWeight = FontWeight;
-                    if (Foreground != null)
-                    {
-                        textBox.Foreground = Foreground;
-                    }
-                }
-
-            }
-            else if (element is TextBlock textBlock)
-            {
-                if (propertyName == nameof(FontFamily))
-                {
-                    textBlock.FontFamily = FontFamily;
-                }
-                else if (propertyName == nameof(FontSize))
-                {
-                    SetTextFontSize(textBlock, TextBlock.FontSizeProperty);
-                }
-                else if (propertyName == nameof(FontStyle))
-                {
-                    textBlock.FontStyle = FontStyle;
-                }
-                else if (propertyName == nameof(FontWeight))
-                {
-                    textBlock.FontWeight = FontWeight;
-                }
-                else if (propertyName == nameof(Foreground))
-                {
-                    textBlock.Foreground = Foreground;
-                }
-                else
-                {
-                    if (FontFamily != null)
-                    {
-                        textBlock.FontFamily = FontFamily;
-                    }
-                    SetTextFontSize(textBlock, TextBlock.FontSizeProperty);
-                    textBlock.FontStyle = FontStyle;
-                    textBlock.FontWeight = FontWeight;
-                    if (Foreground != null)
-                    {
-                        textBlock.Foreground = Foreground;
-                    }
                 }
             }
             else
             {
-                throw DataGridError.DataGrid.ValueIsNotAnInstanceOfEitherOr("element", typeof(TextBox), typeof(TextBlock));
+                throw DataGridError.DataGrid.ValueIsNotAnInstanceOf("element", typeof(AvaloniaObject));
             }
         }
 
-        private void SetTextFontSize(AvaloniaObject textElement, AvaloniaProperty fontSizeProperty)
+        private void SyncProperties(AvaloniaObject content)
         {
-            double newFontSize = FontSize;
+            DataGridHelper.SyncColumnProperty(this, content, FontFamilyProperty);
-            if (double.IsNaN(newFontSize))
+            DataGridHelper.SyncColumnProperty(this, content, FontSizeProperty);
-            {
+            DataGridHelper.SyncColumnProperty(this, content, FontStyleProperty);
-                textElement.ClearValue(fontSizeProperty);
+            DataGridHelper.SyncColumnProperty(this, content, FontWeightProperty);
-            }
+            DataGridHelper.SyncColumnProperty(this, content, ForegroundProperty);
-            else
-            {
-                textElement.SetValue(fontSizeProperty, newFontSize);
-            }
         }
-
     }
 }

src/Avalonia.Controls.DataGrid/Themes/Fluent.xaml

@@ -588,18 +588,11 @@
             <!--<DataGridColumnHeader Name="PART_TopRightCornerHeader"
                                   Grid.Column="2"
                                   Template="{StaticResource TopRightHeaderTemplate}" />-->
-            <!--<Rectangle Name="PART_ColumnHeadersAndRowsSeparator"
+            <Rectangle Name="PART_ColumnHeadersAndRowsSeparator"
                        Grid.ColumnSpan="3"
                        VerticalAlignment="Bottom"
-                       StrokeThickness="1"
                        Height="1"
-                       Fill="{DynamicResource DataGridGridLinesBrush}" />-->
+                       Fill="{DynamicResource DataGridGridLinesBrush}" />
-            <Border Name="PART_ColumnHeadersAndRowsSeparator"
-                    Grid.ColumnSpan="3"
-                    Height="2"
-                    VerticalAlignment="Bottom"
-                    BorderThickness="0,0,0,1"
-                    BorderBrush="{DynamicResource DataGridGridLinesBrush}" />
 
             <DataGridRowsPresenter Name="PART_RowsPresenter"
                                    Grid.Row="1"
@@ -642,4 +635,14 @@
       </ControlTemplate>
     </Setter>
   </Style>
+
+  <Style Selector="DataGrid:empty-columns /template/ DataGridColumnHeader#PART_TopLeftCornerHeader">
+    <Setter Property="IsVisible" Value="False" />
+  </Style>
+  <Style Selector="DataGrid:empty-columns /template/ DataGridColumnHeadersPresenter#PART_ColumnHeadersPresenter">
+    <Setter Property="IsVisible" Value="False" />
+  </Style>
+  <Style Selector="DataGrid:empty-columns /template/ Rectangle#PART_ColumnHeadersAndRowsSeparator">
+    <Setter Property="IsVisible" Value="False" />
+  </Style>
 </Styles>

src/Avalonia.Controls.DataGrid/Utils/DataGridHelper.cs

@@ -0,0 +1,22 @@
+namespace Avalonia.Controls
+{
+    internal static class DataGridHelper
+    {
+        internal static void SyncColumnProperty<T>(AvaloniaObject column, AvaloniaObject content, AvaloniaProperty<T> property)
+        {
+            SyncColumnProperty(column, content, property, property);
+        }
+
+        internal static void SyncColumnProperty<T>(AvaloniaObject column, AvaloniaObject content, AvaloniaProperty<T> contentProperty, AvaloniaProperty<T> columnProperty)
+        {
+            if (!column.IsSet(columnProperty))
+            {
+                content.ClearValue(contentProperty);
+            }
+            else
+            {
+                content.SetValue(contentProperty, column.GetValue(columnProperty));
+            }
+        }
+    }
+}

src/Avalonia.Controls/Calendar/CalendarDatePicker.cs

@@ -420,7 +420,7 @@ namespace Avalonia.Controls
                 _calendar.DayButtonMouseUp -= Calendar_DayButtonMouseUp;
                 _calendar.DisplayDateChanged -= Calendar_DisplayDateChanged;
                 _calendar.SelectedDatesChanged -= Calendar_SelectedDatesChanged;
-                _calendar.PointerPressed -= Calendar_PointerPressed;
+                _calendar.PointerReleased -= Calendar_PointerReleased;
                 _calendar.KeyDown -= Calendar_KeyDown;
             }
             _calendar = e.NameScope.Find<Calendar>(ElementCalendar);
@@ -435,7 +435,7 @@ namespace Avalonia.Controls
                 _calendar.DayButtonMouseUp += Calendar_DayButtonMouseUp;
                 _calendar.DisplayDateChanged += Calendar_DisplayDateChanged;
                 _calendar.SelectedDatesChanged += Calendar_SelectedDatesChanged;
-                _calendar.PointerPressed += Calendar_PointerPressed;
+                _calendar.PointerReleased += Calendar_PointerReleased;
                 _calendar.KeyDown += Calendar_KeyDown;
                 //_calendar.SizeChanged += new SizeChangedEventHandler(Calendar_SizeChanged);
                 //_calendar.IsTabStop = true;
@@ -831,9 +831,10 @@ namespace Avalonia.Controls
                 }
             }
         }
-        private void Calendar_PointerPressed(object sender, PointerPressedEventArgs e)
+        private void Calendar_PointerReleased(object sender, PointerReleasedEventArgs e)
         {
-            if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
+             
+            if (e.InitialPressMouseButton == MouseButton.Left)
             {
                 e.Handled = true;
             }

src/Avalonia.Controls/ComboBox.cs

@@ -257,7 +257,7 @@ namespace Avalonia.Controls
         }
 
         /// <inheritdoc/>
-        protected override void OnPointerPressed(PointerPressedEventArgs e)
+        protected override void OnPointerReleased(PointerReleasedEventArgs e)
         {
             if (!e.Handled)
             {
@@ -276,7 +276,7 @@ namespace Avalonia.Controls
                 }
             }
 
-            base.OnPointerPressed(e);
+            base.OnPointerReleased(e);
         }
 
         /// <inheritdoc/>

src/Avalonia.Controls/Generators/ItemContainerGenerator`1.cs

@@ -47,11 +47,7 @@ namespace Avalonia.Controls.Generators
         {
             var container = item as T;
 
-            if (item == null)
+            if (container != null)
-            {
-                return null;
-            }
-            else if (container != null)
             {
                 return container;
             }

src/Avalonia.Controls/Primitives/Popup.cs

@@ -128,6 +128,7 @@ namespace Avalonia.Controls.Primitives
         public static readonly StyledProperty<bool> TopmostProperty =
             AvaloniaProperty.Register<Popup, bool>(nameof(Topmost));
 
+        private bool _isOpenRequested = false;
         private bool _isOpen;
         private bool _ignoreIsOpenChanged;
         private PopupOpenState? _openState;
@@ -361,17 +362,19 @@ namespace Avalonia.Controls.Primitives
 
             if (placementTarget == null)
             {
-                throw new InvalidOperationException("Popup has no logical parent and PlacementTarget is null");
+                _isOpenRequested = true;
+                return;
             }
             
             var topLevel = placementTarget.VisualRoot as TopLevel;
 
             if (topLevel == null)
             {
-                throw new InvalidOperationException(
+                _isOpenRequested = true;
-                    "Attempted to open a popup not attached to a TopLevel");
+                return;
             }
 
+            _isOpenRequested = false;
             var popupHost = OverlayPopupHost.CreatePopupHost(placementTarget, DependencyResolver);
 
             var handlerCleanup = new CompositeDisposable(5);
@@ -492,6 +495,17 @@ namespace Avalonia.Controls.Primitives
             return new Size();
         }
 
+
+        /// <inheritdoc/>
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+            if (_isOpenRequested)
+            {
+                Open();
+            }
+        }
+
         /// <inheritdoc/>
         protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
@@ -552,6 +566,7 @@ namespace Avalonia.Controls.Primitives
 
         private void CloseCore()
         {
+            _isOpenRequested = false;
             if (_openState is null)
             {
                 using (BeginIgnoringIsOpen())

src/Avalonia.Themes.Default/ComboBox.xaml

@@ -26,6 +26,7 @@
     <Setter Property="Padding" Value="4" />
     <Setter Property="MinHeight" Value="20" />
     <Setter Property="PlaceholderForeground" Value="{DynamicResource ThemeForegroundBrush}" />
+    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled" />
     <Setter Property="Template">
       <ControlTemplate>
         <Border Name="border"
@@ -69,7 +70,8 @@
                    IsLightDismissEnabled="True">
               <Border BorderBrush="{DynamicResource ThemeBorderMidBrush}"
                       BorderThickness="1">
-                <ScrollViewer>
+                <ScrollViewer HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
+                              VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}">
                   <ItemsPresenter Name="PART_ItemsPresenter"
                                   Items="{TemplateBinding Items}"
                                   ItemsPanel="{TemplateBinding ItemsPanel}"

src/Avalonia.Themes.Default/MenuItem.xaml

@@ -64,7 +64,7 @@
               <Border Background="{TemplateBinding Background}"
                       BorderBrush="{DynamicResource ThemeBorderMidBrush}"
                       BorderThickness="{TemplateBinding BorderThickness}">
-                <ScrollViewer>                  
+                <ScrollViewer Classes="menuscroller">                  
                     <ItemsPresenter Name="PART_ItemsPresenter"
                                     Items="{TemplateBinding Items}"
                                     ItemsPanel="{TemplateBinding ItemsPanel}"

src/Avalonia.Themes.Fluent/ComboBox.xaml

@@ -133,7 +133,8 @@
                     Padding="{DynamicResource ComboBoxDropdownBorderPadding}"
                     HorizontalAlignment="Stretch"
                     CornerRadius="{DynamicResource OverlayCornerRadius}">
-              <ScrollViewer>
+              <ScrollViewer HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
+                            VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}">
                 <ItemsPresenter Name="PART_ItemsPresenter"
                                 Items="{TemplateBinding Items}"
                                 Margin="{DynamicResource ComboBoxDropdownContentMargin}"

src/Avalonia.Themes.Fluent/ContextMenu.xaml

@@ -49,7 +49,7 @@
               MinHeight="{TemplateBinding MinHeight}"
               HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
               CornerRadius="{DynamicResource OverlayCornerRadius}">
-        <ScrollViewer>
+        <ScrollViewer Classes="menuscroller">
           <ItemsPresenter Name="PART_ItemsPresenter"
                           Items="{TemplateBinding Items}"
                           ItemsPanel="{TemplateBinding ItemsPanel}"

src/Avalonia.Themes.Fluent/MenuItem.xaml

@@ -123,7 +123,7 @@
                     MinHeight="{DynamicResource MenuFlyoutThemeMinHeight}"
                     HorizontalAlignment="Stretch"
                     CornerRadius="{DynamicResource OverlayCornerRadius}">
-              <ScrollViewer>
+              <ScrollViewer Classes="menuscroller">
                 <ItemsPresenter Name="PART_ItemsPresenter"
                                 Items="{TemplateBinding Items}"
                                 ItemsPanel="{TemplateBinding ItemsPanel}"
@@ -171,7 +171,7 @@
                       MinHeight="{DynamicResource MenuFlyoutThemeMinHeight}"
                       HorizontalAlignment="Stretch"
                       CornerRadius="{DynamicResource OverlayCornerRadius}">
-                <ScrollViewer>
+                <ScrollViewer Classes="menuscroller">
                   <ItemsPresenter Name="PART_ItemsPresenter"
                                   Items="{TemplateBinding Items}"
                                   ItemsPanel="{TemplateBinding ItemsPanel}"

src/Avalonia.Themes.Fluent/ScrollViewer.xaml

@@ -1,5 +1,21 @@
-<Styles xmlns="https://github.com/avaloniaui" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:converters="clr-namespace:Avalonia.Controls.Converters;assembly=Avalonia.Controls">
 
+  <Design.PreviewWith>
+    <Grid ColumnDefinitions="*,20,*"
+          Height="300"
+          Width="200"
+          Margin="20">
+      <ScrollViewer>
+        <Border Height="1000" Background="#ccc"/>
+      </ScrollViewer>
+      <ScrollViewer Grid.Column="2" Classes="menuscroller">
+        <Border Height="1000" Background="#ccc"/>
+      </ScrollViewer>
+    </Grid>
+  </Design.PreviewWith>
+  
   <Style Selector="ScrollViewer">
     <Setter Property="Background"
             Value="Transparent" />
@@ -66,4 +82,78 @@
     <Setter Property="Opacity" Value="1" />
   </Style>
 
+  <Style Selector="ScrollViewer.menuscroller">
+    <Setter Property="Template">
+      <ControlTemplate>
+        <DockPanel>
+          <RepeatButton DockPanel.Dock="Top"
+                        BorderThickness="0"
+                        Background="Transparent"
+                        HorizontalAlignment="Stretch"
+                        HorizontalContentAlignment="Center"
+                        RenderTransform="{x:Null}"
+                        Command="{Binding LineUp, RelativeSource={RelativeSource TemplatedParent}}">
+            <RepeatButton.IsVisible>
+              <MultiBinding Converter="{x:Static converters:MenuScrollingVisibilityConverter.Instance}"
+                            ConverterParameter="0">
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="VerticalScrollBarVisibility"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Offset.Y"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Extent.Height"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Viewport.Height"/>
+              </MultiBinding>
+            </RepeatButton.IsVisible>
+            <Viewbox Width="{DynamicResource ScrollBarButtonArrowIconFontSize}"
+                     Height="{DynamicResource ScrollBarButtonArrowIconFontSize}">
+              <Path VerticalAlignment="Center"
+                    HorizontalAlignment="Center"
+                    Data="M 19.091797 14.970703 L 10 5.888672 L 0.908203 14.970703 L 0.029297 14.091797 L 10 4.111328 L 19.970703 14.091797 Z"
+                    Width="20"
+                    Height="20" />
+            </Viewbox>
+          </RepeatButton>
+          <RepeatButton DockPanel.Dock="Bottom"
+                        BorderThickness="0"
+                        Background="Transparent"
+                        HorizontalAlignment="Stretch"
+                        HorizontalContentAlignment="Center"
+                        RenderTransform="{x:Null}"
+                        Command="{Binding LineDown, RelativeSource={RelativeSource TemplatedParent}}">
+            <RepeatButton.IsVisible>
+              <MultiBinding Converter="{x:Static converters:MenuScrollingVisibilityConverter.Instance}"
+                            ConverterParameter="100">
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="VerticalScrollBarVisibility"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Offset.Y"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Extent.Height"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Viewport.Height"/>
+              </MultiBinding>
+            </RepeatButton.IsVisible>
+            <Viewbox Width="{DynamicResource ScrollBarButtonArrowIconFontSize}"
+                     Height="{DynamicResource ScrollBarButtonArrowIconFontSize}">
+              <Path VerticalAlignment="Center"
+                    HorizontalAlignment="Center"
+                    Data="M 18.935547 4.560547 L 19.814453 5.439453 L 10 15.253906 L 0.185547 5.439453 L 1.064453 4.560547 L 10 13.496094 Z"
+                    Width="20"
+                    Height="20" />
+            </Viewbox>
+          </RepeatButton>
+          <ScrollContentPresenter Name="PART_ContentPresenter"
+                                  CanHorizontallyScroll="{TemplateBinding CanHorizontallyScroll}"
+                                  CanVerticallyScroll="{TemplateBinding CanVerticallyScroll}"
+                                  Content="{TemplateBinding Content}"
+                                  Extent="{TemplateBinding Extent, Mode=TwoWay}"
+                                  Margin="{TemplateBinding Padding}"
+                                  Offset="{TemplateBinding Offset, Mode=TwoWay}"
+                                  Viewport="{TemplateBinding Viewport, Mode=TwoWay}"/>
+        </DockPanel>
+      </ControlTemplate>
+    </Setter>
+  </Style>
+  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton > Viewbox > Path">
+    <Setter Property="Fill" Value="{DynamicResource ScrollBarButtonArrowForeground}" />
+  </Style>
+
+  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton:pointerover > Viewbox > Path">
+    <Setter Property="Fill" Value="{DynamicResource ScrollBarButtonArrowForegroundPointerOver}" />
+  </Style>
+
 </Styles>

tests/Avalonia.Base.UnitTests/Data/Core/Plugins/DataAnnotationsValidationPluginTests.cs

@@ -59,12 +59,12 @@ namespace Avalonia.Markup.UnitTests.Data.Plugins
             {
                 new BindingNotification(5),
                 new BindingNotification(
-                    new ValidationException(errmsg),
+                    new DataValidationException(errmsg),
                     BindingErrorType.DataValidationError,
                     3),
                 new BindingNotification(7),
                 new BindingNotification(
-                    new ValidationException(errmsg),
+                    new DataValidationException(errmsg),
                     BindingErrorType.DataValidationError,
                     11),
             }, result);

tests/Avalonia.Controls.UnitTests/ComboBoxTests.cs

@@ -2,7 +2,6 @@ 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;
 using Avalonia.UnitTests;
@@ -27,6 +26,7 @@ namespace Avalonia.Controls.UnitTests
             Assert.True(target.IsDropDownOpen);
 
             _helper.Down(target);
+            _helper.Up(target);
 
             Assert.False(target.IsDropDownOpen);
         }

tests/Avalonia.Controls.UnitTests/Generators/ItemContainerGeneratorTests.cs

@@ -144,6 +144,16 @@ namespace Avalonia.Controls.UnitTests.Generators
             Assert.Equal("bar", container.Content);
         }
 
+        [Fact]
+        public void Materialize_Should_Create_Containers_When_Item_Is_Null()
+        {
+            var owner = new Decorator();
+            var target = new ItemContainerGenerator<ListBoxItem>(owner, ListBoxItem.ContentProperty, null);
+            var container = (ListBoxItem)target.Materialize(0, null).ContainerControl;
+
+            Assert.True(container != null, "The containers is not materialized.");
+        }
+
         private IList<ItemContainerInfo> Materialize(
             IItemContainerGenerator generator,
             int index,

tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs

@@ -21,7 +21,50 @@ namespace Avalonia.Controls.UnitTests.Primitives
     public class PopupTests
     {
         protected bool UsePopupHost;
-        
+
+        [Fact]
+        public void Popup_Open_Without_Target_Should_Attach_Itself_Later()
+        {
+            using (CreateServices())
+            {
+                int openedEvent = 0;
+                var target = new Popup();
+                target.Opened += (s, a) => openedEvent++;
+                target.IsOpen = true;
+
+                var window = PreparedWindow(target);
+                window.Show();
+                Assert.Equal(1, openedEvent);
+            }
+        }
+
+        [Fact]
+        public void Popup_Without_TopLevel_Shouldnt_Call_Open()
+        {
+            int openedEvent = 0;
+            var target = new Popup();
+            target.Opened += (s, a) => openedEvent++;
+            target.IsOpen = true;
+
+            Assert.Equal(0, openedEvent);
+        }
+
+        [Fact]
+        public void Opening_Popup_Shouldnt_Throw_When_Not_In_Visual_Tree()
+        {
+            var target = new Popup();
+            target.IsOpen = true;
+        }
+
+        [Fact]
+        public void Opening_Popup_Shouldnt_Throw_When_In_Tree_Without_TopLevel()
+        {
+            Control c = new Control();
+            var target = new Popup();
+            ((ISetLogicalParent)target).SetParent(c);
+            target.IsOpen = true;
+        }
+
         [Fact]
         public void Setting_Child_Should_Set_Child_Controls_LogicalParent()
         {

tests/Avalonia.Visuals.UnitTests/Media/GlyphRunTests.cs

@@ -119,6 +119,56 @@ namespace Avalonia.Visuals.UnitTests.Media
             }
         }
 
+        [InlineData(new double[] { 10, 10, 10 }, new ushort[] { 0, 0, 0 }, 0)]
+        [InlineData(new double[] { 10, 10, 10 }, new ushort[] { 0, 0, 0 }, 1)]
+        [InlineData(new double[] { 10, 10, 10, 10 }, new ushort[] { 0, 0, 0, 3 }, 0)]
+        [InlineData(new double[] { 10, 10, 10, 10 }, new ushort[] { 3, 0, 0, 0 }, 1)]
+        [InlineData(new double[] { 10, 10, 10, 10, 10 }, new ushort[] { 0, 1, 1, 1, 4 }, 0)]
+        [InlineData(new double[] { 10, 10, 10, 10, 10 }, new ushort[] { 4, 1, 1, 1, 0 }, 1)]
+        [Theory]
+        public void Should_Find_Glyph_Index(double[] advances, ushort[] clusters, int bidiLevel)
+        {
+            using (var glyphRun = CreateGlyphRun(advances, clusters, bidiLevel))
+            {
+                if (glyphRun.IsLeftToRight)
+                {
+                    for (var i = 0; i < clusters.Length; i++)
+                    {
+                        var cluster = clusters[i];
+
+                        var found = glyphRun.FindGlyphIndex(cluster);
+
+                        var expected = i;
+
+                        while (expected - 1 >= 0 && clusters[expected - 1] == cluster)
+                        {
+                            expected--;
+                        }
+
+                        Assert.Equal(expected, found);
+                    }
+                }
+                else
+                {
+                    for (var i = clusters.Length - 1; i > 0; i--)
+                    {
+                        var cluster = clusters[i];
+
+                        var found = glyphRun.FindGlyphIndex(cluster);
+
+                        var expected = i;
+
+                        while (expected + 1 < clusters.Length && clusters[expected + 1] == cluster)
+                        {
+                            expected++;
+                        }
+
+                        Assert.Equal(expected, found);
+                    }
+                }
+            }
+        }
+
         private static GlyphRun CreateGlyphRun(double[] glyphAdvances, ushort[] glyphClusters, int bidiLevel = 0)
         {
             var count = glyphAdvances.Length;