diff --git a/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml b/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml
index f90a0c4658..a49616e543 100644
--- a/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml
@@ -51,6 +51,11 @@
                          Width="200"
                          Margin="0,0,0,8"
                          FilterMode="None"/>
+        <TextBlock Text="Custom Autocomplete"/>
+        <AutoCompleteBox Name="CustomAutocompleteBox"
+                         Width="200"
+                         Margin="0,0,0,8"
+                         FilterMode="None"/>
       </StackPanel>
     </StackPanel>
   </StackPanel>
diff --git a/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs b/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs
index f9d6a72a3a..574cc79a7d 100644
--- a/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs
@@ -92,13 +92,28 @@ namespace ControlCatalog.Pages
         }
         public StateData[] States { get; private set; }
         
+        private LinkedList<string>[] BuildAllSentences()
+        {
+            return new string[]
+            {
+                "Hello world",
+                "No this is Patrick",
+                "Never gonna give you up",
+                "How does one patch KDE2 under FreeBSD"
+            }
+            .Select(x => new LinkedList<string>(x.Split(' ')))
+            .ToArray();
+        }
+        public LinkedList<string>[] Sentences { get; private set; }
+
         public AutoCompleteBoxPage()
         {
             this.InitializeComponent();
 
             States = BuildAllStates();
+            Sentences = BuildAllSentences();
 
-            foreach (AutoCompleteBox box in GetAllAutoCompleteBox())
+            foreach (AutoCompleteBox box in GetAllAutoCompleteBox().Where(x => x.Name != "CustomAutocompleteBox"))
             {
                 box.Items = States;
             }
@@ -116,6 +131,11 @@ namespace ControlCatalog.Pages
 
             var asyncBox = this.FindControl<AutoCompleteBox>("AsyncBox");
             asyncBox.AsyncPopulator = PopulateAsync;
+
+            var customAutocompleteBox = this.FindControl<AutoCompleteBox>("CustomAutocompleteBox");
+            customAutocompleteBox.Items = Sentences.SelectMany(x => x);
+            customAutocompleteBox.TextFilter = LastWordContains;
+            customAutocompleteBox.TextSelector = AppendWord;
         }
         private IEnumerable<AutoCompleteBox> GetAllAutoCompleteBox()
         {
@@ -137,6 +157,42 @@ namespace ControlCatalog.Pages
                       .ToList();
         }
 
+        private bool LastWordContains(string searchText, string item)
+        {
+            var words = searchText.Split(' ');
+            var options = Sentences.Select(x => x.First).ToArray();
+            for (var i = 0; i < words.Length; ++i)
+            {
+                var word = words[i];
+                for (var j = 0; j < options.Length; ++j)
+                {
+                    var option = options[j];
+                    if (option == null)
+                        continue;
+
+                    if (i == words.Length - 1)
+                    {
+                        options[j] = option.Value.ToLower().Contains(word.ToLower()) ? option : null;
+                    }
+                    else
+                    {
+                        options[j] = option.Value.Equals(word, StringComparison.InvariantCultureIgnoreCase) ? option.Next : null;
+                    }
+                }
+            }
+
+            return options.Any(x => x != null && x.Value == item);
+        }
+        private string AppendWord(string text, string item)
+        {
+            string[] parts = text.Split(' ');
+            if (parts.Length == 0)
+                return item;
+
+            parts[parts.Length - 1] = item;
+            return string.Join(" ", parts);
+        }
+
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);
diff --git a/samples/RenderDemo/MainWindow.xaml b/samples/RenderDemo/MainWindow.xaml
index 770960d7c4..93fbe5e412 100644
--- a/samples/RenderDemo/MainWindow.xaml
+++ b/samples/RenderDemo/MainWindow.xaml
@@ -3,8 +3,8 @@
         x:Class="RenderDemo.MainWindow"
         Title="AvaloniaUI Rendering Test"
         xmlns:pages="clr-namespace:RenderDemo.Pages"
-        Width="800"
-        Height="600">
+        Width="{Binding Width, Mode=TwoWay}"
+        Height="{Binding Height, Mode=TwoWay}">
   <DockPanel>
     <Menu DockPanel.Dock="Top">
       <MenuItem Header="Rendering">
@@ -24,6 +24,10 @@
           </MenuItem.Icon>
         </MenuItem>
       </MenuItem>
+      <MenuItem Header="Tests">
+        <MenuItem Header="Resize window"
+                  Command="{Binding ResizeWindow}"/>
+      </MenuItem>
     </Menu>
     <TabControl Classes="sidebar">
       <TabItem Header="Animations">
diff --git a/samples/RenderDemo/ViewModels/MainWindowViewModel.cs b/samples/RenderDemo/ViewModels/MainWindowViewModel.cs
index d2d789a687..eda5e80530 100644
--- a/samples/RenderDemo/ViewModels/MainWindowViewModel.cs
+++ b/samples/RenderDemo/ViewModels/MainWindowViewModel.cs
@@ -1,5 +1,6 @@
-using System;
-using System.Reactive;
+using System.Reactive;
+using System.Threading.Tasks;
+
 using ReactiveUI;
 
 namespace RenderDemo.ViewModels
@@ -8,26 +9,61 @@ namespace RenderDemo.ViewModels
     {
         private bool drawDirtyRects = false;
         private bool drawFps = true;
+        private double width = 800;
+        private double height = 600;
 
         public MainWindowViewModel()
         {
             ToggleDrawDirtyRects = ReactiveCommand.Create(() => DrawDirtyRects = !DrawDirtyRects);
             ToggleDrawFps = ReactiveCommand.Create(() => DrawFps = !DrawFps);
+            ResizeWindow = ReactiveCommand.CreateFromTask(ResizeWindowAsync);
         }
 
         public bool DrawDirtyRects
         {
-            get { return drawDirtyRects; }
-            set { this.RaiseAndSetIfChanged(ref drawDirtyRects, value); }
+            get => drawDirtyRects;
+            set => this.RaiseAndSetIfChanged(ref drawDirtyRects, value);
         }
 
         public bool DrawFps
         {
-            get { return drawFps; }
-            set { this.RaiseAndSetIfChanged(ref drawFps, value); }
+            get => drawFps;
+            set => this.RaiseAndSetIfChanged(ref drawFps, value);
+        }
+
+        public double Width
+        {
+            get => width;
+            set => this.RaiseAndSetIfChanged(ref width, value);
+        }
+
+        public double Height
+        {
+            get => height;
+            set => this.RaiseAndSetIfChanged(ref height, value);
         }
 
         public ReactiveCommand<Unit, bool> ToggleDrawDirtyRects { get; }
         public ReactiveCommand<Unit, bool> ToggleDrawFps { get; }
+        public ReactiveCommand<Unit, Unit> ResizeWindow { get; }
+
+        private async Task ResizeWindowAsync()
+        {
+            for (int i = 0; i < 30; i++)
+            {
+                Width += 10;
+                Height += 5;
+                await Task.Delay(10);
+            }
+
+            await Task.Delay(10);
+
+            for (int i = 0; i < 30; i++)
+            {
+                Width -= 10;
+                Height -= 5;
+                await Task.Delay(10);
+            }
+        }
     }
 }
diff --git a/src/Avalonia.Controls.DataGrid/DataGrid.cs b/src/Avalonia.Controls.DataGrid/DataGrid.cs
index 9ca0b91523..7c57ea3db9 100644
--- a/src/Avalonia.Controls.DataGrid/DataGrid.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGrid.cs
@@ -24,12 +24,14 @@ using Avalonia.Input.Platform;
 using System.ComponentModel.DataAnnotations;
 using Avalonia.Controls.Utils;
 using Avalonia.Layout;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// Displays data in a customizable grid.
     /// </summary>
+    [PseudoClasses(":invalid")]
     public partial class DataGrid : TemplatedControl
     {
         private const string DATAGRID_elementRowsPresenterName = "PART_RowsPresenter";
diff --git a/src/Avalonia.Controls.DataGrid/DataGridCell.cs b/src/Avalonia.Controls.DataGrid/DataGridCell.cs
index e5fbfa1a81..445dc541a7 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridCell.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridCell.cs
@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Input;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> cell.
     /// </summary>
+    [PseudoClasses(":selected", ":current", ":edited", ":invalid")]
     public class DataGridCell : ContentControl
     {
         private const string DATAGRIDCELL_elementRightGridLine = "PART_RightGridLine";
diff --git a/src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs b/src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs
index 25aae99942..856d1f6566 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs
@@ -14,12 +14,14 @@ using Avalonia.Utilities;
 using System;
 using Avalonia.Controls.Utils;
 using Avalonia.Controls.Mixins;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> column header.
     /// </summary>
+    [PseudoClasses(":dragIndicator", ":pressed", ":sortascending", ":sortdescending")]
     public class DataGridColumnHeader : ContentControl
     {
         private enum DragMode
diff --git a/src/Avalonia.Controls.DataGrid/DataGridRow.cs b/src/Avalonia.Controls.DataGrid/DataGridRow.cs
index d5ce8dba75..c3562c53a4 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridRow.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridRow.cs
@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
@@ -20,6 +21,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a <see cref="T:Avalonia.Controls.DataGrid" /> row.
     /// </summary>
+    [PseudoClasses(":selected", ":editing", ":invalid")]
     public class DataGridRow : TemplatedControl
     {
 
diff --git a/src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs b/src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs
index 0833247439..1e03b134b1 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs
@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
@@ -13,6 +14,7 @@ using System.Reactive.Linq;
 
 namespace Avalonia.Controls
 {
+    [PseudoClasses(":pressed", ":current", ":expanded")]
     public class DataGridRowGroupHeader : TemplatedControl
     {
         private const string DATAGRIDROWGROUPHEADER_expanderButton = "ExpanderButton";
diff --git a/src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs b/src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs
index 8f8b1742ba..0cd3589a57 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs
@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 using Avalonia.Media;
 using System.Diagnostics;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> row header. 
     /// </summary>
+    [PseudoClasses(":invalid", ":selected", ":editing", ":current")]
     public class DataGridRowHeader : ContentControl
     {
         private const string DATAGRIDROWHEADER_elementRootName = "PART_Root";
diff --git a/src/Avalonia.Controls/AutoCompleteBox.cs b/src/Avalonia.Controls/AutoCompleteBox.cs
index c164f282e8..bfd633c947 100644
--- a/src/Avalonia.Controls/AutoCompleteBox.cs
+++ b/src/Avalonia.Controls/AutoCompleteBox.cs
@@ -14,6 +14,7 @@ using System.Reactive.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Avalonia.Collections;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Controls.Utils;
@@ -30,6 +31,7 @@ namespace Avalonia.Controls
     /// <see cref="E:Avalonia.Controls.AutoCompleteBox.Populated" />
     /// event.
     /// </summary>
+    [PseudoClasses(":dropdownopen")]
     public class PopulatedEventArgs : EventArgs
     {
         /// <summary>
@@ -225,6 +227,27 @@ namespace Avalonia.Controls
         Custom = 13,
     }
 
+    /// <summary>
+    /// Represents the selector used by the
+    /// <see cref="T:Avalonia.Controls.AutoCompleteBox" /> control to
+    /// determine how the specified text should be modified with an item.
+    /// </summary>
+    /// <returns>
+    /// Modified text that will be used by the
+    /// <see cref="T:Avalonia.Controls.AutoCompleteBox" />.
+    /// </returns>
+    /// <param name="search">The string used as the basis for filtering.</param>
+    /// <param name="item">
+    /// The selected item that should be combined with the
+    /// <paramref name="search" /> parameter.
+    /// </param>
+    /// <typeparam name="T">
+    /// The type used for filtering the
+    /// <see cref="T:Avalonia.Controls.AutoCompleteBox" />.
+    /// This type can be either a string or an object.
+    /// </typeparam>
+    public delegate string AutoCompleteSelector<T>(string search, T item);
+
     /// <summary>
     /// Represents a control that provides a text box for user input and a
     /// drop-down that contains possible matches based on the input in the text
@@ -362,6 +385,9 @@ namespace Avalonia.Controls
         private AutoCompleteFilterPredicate<object> _itemFilter;
         private AutoCompleteFilterPredicate<string> _textFilter = AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.StartsWith);
 
+        private AutoCompleteSelector<object> _itemSelector;
+        private AutoCompleteSelector<string> _textSelector;
+
         public static readonly RoutedEvent<SelectionChangedEventArgs> SelectionChangedEvent =
             RoutedEvent.Register<SelectionChangedEventArgs>(nameof(SelectionChanged), RoutingStrategies.Bubble, typeof(AutoCompleteBox));
 
@@ -528,6 +554,34 @@ namespace Avalonia.Controls
                 (o, v) => o.TextFilter = v,
                 unsetValue: AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.StartsWith));
 
+        /// <summary>
+        /// Identifies the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemSelector" />
+        /// dependency property.
+        /// </summary>
+        /// <value>The identifier for the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemSelector" />
+        /// dependency property.</value>
+        public static readonly DirectProperty<AutoCompleteBox, AutoCompleteSelector<object>> ItemSelectorProperty =
+            AvaloniaProperty.RegisterDirect<AutoCompleteBox, AutoCompleteSelector<object>>(
+                nameof(ItemSelector),
+                o => o.ItemSelector,
+                (o, v) => o.ItemSelector = v);
+
+        /// <summary>
+        /// Identifies the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.TextSelector" />
+        /// dependency property.
+        /// </summary>
+        /// <value>The identifier for the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.TextSelector" />
+        /// dependency property.</value>
+        public static readonly DirectProperty<AutoCompleteBox, AutoCompleteSelector<string>> TextSelectorProperty =
+            AvaloniaProperty.RegisterDirect<AutoCompleteBox, AutoCompleteSelector<string>>(
+                nameof(TextSelector),
+                o => o.TextSelector,
+                (o, v) => o.TextSelector = v);
+
         /// <summary>
         /// Identifies the
         /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />
@@ -1061,6 +1115,40 @@ namespace Avalonia.Controls
             set { SetAndRaise(TextFilterProperty, ref _textFilter, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />.
+        /// </summary>
+        /// <value>
+        /// The custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />.
+        /// </value>
+        public AutoCompleteSelector<object> ItemSelector
+        {
+            get { return _itemSelector; }
+            set { SetAndRaise(ItemSelectorProperty, ref _itemSelector, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />
+        /// in a text-based way.
+        /// </summary>
+        /// <value>
+        /// The custom method that combines the user-entered
+        /// text and one of the items specified by the
+        /// <see cref="P:Avalonia.Controls.AutoCompleteBox.ItemsSource" />
+        /// in a text-based way.
+        /// </value>
+        public AutoCompleteSelector<string> TextSelector
+        {
+            get { return _textSelector; }
+            set { SetAndRaise(TextSelectorProperty, ref _textSelector, value); }
+        }
+
         public Func<string, CancellationToken, Task<IEnumerable<object>>> AsyncPopulator
         {
             get { return _asyncPopulator; }
@@ -2329,6 +2417,14 @@ namespace Avalonia.Controls
             {
                 text = SearchText;
             }
+            else if (TextSelector != null)
+            {
+                text = TextSelector(SearchText, FormatValue(newItem, true));
+            }
+            else if (ItemSelector != null)
+            {
+                text = ItemSelector(SearchText, newItem);
+            }
             else
             {
                 text = FormatValue(newItem, true);
diff --git a/src/Avalonia.Controls/Button.cs b/src/Avalonia.Controls/Button.cs
index b54eb2ac57..e94d00b2ff 100644
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Windows.Input;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -28,6 +29,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A button control.
     /// </summary>
+    [PseudoClasses(":pressed")]
     public class Button : ContentControl
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/ButtonSpinner.cs b/src/Avalonia.Controls/ButtonSpinner.cs
index 44f66d397a..5fe2cf3704 100644
--- a/src/Avalonia.Controls/ButtonSpinner.cs
+++ b/src/Avalonia.Controls/ButtonSpinner.cs
@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Data;
 using Avalonia.Input;
@@ -15,6 +16,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a spinner control that includes two Buttons.
     /// </summary>
+    [PseudoClasses(":left", ":right")]
     public class ButtonSpinner : Spinner
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Calendar/CalendarButton.cs b/src/Avalonia.Controls/Calendar/CalendarButton.cs
index 80370df145..76af933b55 100644
--- a/src/Avalonia.Controls/Calendar/CalendarButton.cs
+++ b/src/Avalonia.Controls/Calendar/CalendarButton.cs
@@ -3,6 +3,7 @@
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
 
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 using System;
 
@@ -12,6 +13,7 @@ namespace Avalonia.Controls.Primitives
     /// Represents a button on a
     /// <see cref="T:Avalonia.Controls.Calendar" />.
     /// </summary>
+    [PseudoClasses(":selected", ":inactive", ":btnfocused")]
     public sealed class CalendarButton : Button
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Calendar/CalendarDayButton.cs b/src/Avalonia.Controls/Calendar/CalendarDayButton.cs
index 3a39bd10fa..d5748bb9e4 100644
--- a/src/Avalonia.Controls/Calendar/CalendarDayButton.cs
+++ b/src/Avalonia.Controls/Calendar/CalendarDayButton.cs
@@ -5,10 +5,12 @@
 
 using System;
 using System.Globalization;
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 
 namespace Avalonia.Controls.Primitives
 {
+    [PseudoClasses(":pressed", ":disabled", ":selected", ":inactive", ":today", ":blackout", ":dayfocused")]
     public sealed class CalendarDayButton : Button
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Calendar/CalendarItem.cs b/src/Avalonia.Controls/Calendar/CalendarItem.cs
index 0be7c4f67e..e9ea942142 100644
--- a/src/Avalonia.Controls/Calendar/CalendarItem.cs
+++ b/src/Avalonia.Controls/Calendar/CalendarItem.cs
@@ -7,6 +7,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -18,6 +19,7 @@ namespace Avalonia.Controls.Primitives
     /// Represents the currently displayed month or year on a
     /// <see cref="T:Avalonia.Controls.Calendar" />.
     /// </summary>
+    [PseudoClasses(":calendardisabled")]
     public sealed class CalendarItem : TemplatedControl
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Chrome/CaptionButtons.cs b/src/Avalonia.Controls/Chrome/CaptionButtons.cs
index a86cbc271b..cd60130c5b 100644
--- a/src/Avalonia.Controls/Chrome/CaptionButtons.cs
+++ b/src/Avalonia.Controls/Chrome/CaptionButtons.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Disposables;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 
 #nullable enable
@@ -9,6 +10,7 @@ namespace Avalonia.Controls.Chrome
     /// <summary>
     /// Draws window minimize / maximize / close buttons in a <see cref="TitleBar"/> when managed client decorations are enabled.
     /// </summary>
+    [PseudoClasses(":minimized", ":normal", ":maximized", ":fullscreen")]
     public class CaptionButtons : TemplatedControl
     {
         private CompositeDisposable? _disposables;
diff --git a/src/Avalonia.Controls/Chrome/TitleBar.cs b/src/Avalonia.Controls/Chrome/TitleBar.cs
index c0c8076dd8..fbddb06952 100644
--- a/src/Avalonia.Controls/Chrome/TitleBar.cs
+++ b/src/Avalonia.Controls/Chrome/TitleBar.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Disposables;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 
 #nullable enable
@@ -9,6 +10,7 @@ namespace Avalonia.Controls.Chrome
     /// <summary>
     /// Draws a titlebar when managed client decorations are enabled.
     /// </summary>
+    [PseudoClasses(":minimized", ":normal", ":maximized", ":fullscreen")]
     public class TitleBar : TemplatedControl
     {
         private CompositeDisposable? _disposables;
diff --git a/src/Avalonia.Controls/DataValidationErrors.cs b/src/Avalonia.Controls/DataValidationErrors.cs
index dfe9a16532..3c64691816 100644
--- a/src/Avalonia.Controls/DataValidationErrors.cs
+++ b/src/Avalonia.Controls/DataValidationErrors.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Linq;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Templates;
 using Avalonia.Data;
 
@@ -14,6 +15,7 @@ namespace Avalonia.Controls
     /// <remarks>
     /// You will probably only want to create instances inside of control templates.
     /// </remarks>
+    [PseudoClasses(":error")]
     public class DataValidationErrors : ContentControl
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/DateTimePickers/DatePicker.cs b/src/Avalonia.Controls/DateTimePickers/DatePicker.cs
index a41c159980..8d893154eb 100644
--- a/src/Avalonia.Controls/DateTimePickers/DatePicker.cs
+++ b/src/Avalonia.Controls/DateTimePickers/DatePicker.cs
@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
 using Avalonia.Interactivity;
@@ -11,6 +12,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control to allow the user to select a date
     /// </summary>
+    [PseudoClasses(":hasnodate")]
     public class DatePicker : TemplatedControl
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/DateTimePickers/TimePicker.cs b/src/Avalonia.Controls/DateTimePickers/TimePicker.cs
index e54da1fb3a..e4ff5e9e5b 100644
--- a/src/Avalonia.Controls/DateTimePickers/TimePicker.cs
+++ b/src/Avalonia.Controls/DateTimePickers/TimePicker.cs
@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
 using System;
@@ -9,6 +10,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control to allow the user to select a time
     /// </summary>
+    [PseudoClasses(":hasnotime")]
     public class TimePicker : TemplatedControl
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Expander.cs b/src/Avalonia.Controls/Expander.cs
index 43882b70c8..9ff2e41fa9 100644
--- a/src/Avalonia.Controls/Expander.cs
+++ b/src/Avalonia.Controls/Expander.cs
@@ -1,6 +1,6 @@
 using Avalonia.Animation;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
-using Avalonia.Data;
 
 namespace Avalonia.Controls
 {
@@ -12,6 +12,7 @@ namespace Avalonia.Controls
         Right
     }
 
+    [PseudoClasses(":expanded", ":up", ":down", ":left", ":right")]
     public class Expander : HeaderedContentControl
     {
         public static readonly StyledProperty<IPageTransition> ContentTransitionProperty =
diff --git a/src/Avalonia.Controls/ItemsControl.cs b/src/Avalonia.Controls/ItemsControl.cs
index a3dfe33641..3aec06e4eb 100644
--- a/src/Avalonia.Controls/ItemsControl.cs
+++ b/src/Avalonia.Controls/ItemsControl.cs
@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.Collections.Specialized;
 using Avalonia.Collections;
 using Avalonia.Controls.Generators;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
@@ -18,6 +19,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Displays a collection of items.
     /// </summary>
+    [PseudoClasses(":empty", ":singleitem")]
     public class ItemsControl : TemplatedControl, IItemsPresenterHost, ICollectionChangedListener
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/ListBoxItem.cs b/src/Avalonia.Controls/ListBoxItem.cs
index e04c79987f..4fe5f4de40 100644
--- a/src/Avalonia.Controls/ListBoxItem.cs
+++ b/src/Avalonia.Controls/ListBoxItem.cs
@@ -1,3 +1,4 @@
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Input;
 
@@ -6,6 +7,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A selectable item in a <see cref="ListBox"/>.
     /// </summary>
+    [PseudoClasses(":pressed", ":selected")]
     public class ListBoxItem : ContentControl, ISelectable
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/MenuItem.cs b/src/Avalonia.Controls/MenuItem.cs
index b4d3272471..3d8ab3ae48 100644
--- a/src/Avalonia.Controls/MenuItem.cs
+++ b/src/Avalonia.Controls/MenuItem.cs
@@ -4,6 +4,7 @@ using System.Linq;
 using System.Reactive.Linq;
 using System.Windows.Input;
 using Avalonia.Controls.Generators;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
@@ -20,6 +21,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A menu item control.
     /// </summary>
+    [PseudoClasses(":separator", ":icon", ":open", ":pressed", ":selected")]
     public class MenuItem : HeaderedSelectingItemsControl, IMenuItem, ISelectable
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Notifications/NotificationCard.cs b/src/Avalonia.Controls/Notifications/NotificationCard.cs
index f90746bf06..cdbace3ced 100644
--- a/src/Avalonia.Controls/Notifications/NotificationCard.cs
+++ b/src/Avalonia.Controls/Notifications/NotificationCard.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Reactive.Linq;
+using Avalonia.Controls.Metadata;
 using Avalonia.Interactivity;
 using Avalonia.LogicalTree;
 
@@ -9,6 +10,7 @@ namespace Avalonia.Controls.Notifications
     /// <summary>
     /// Control that represents and displays a notification.
     /// </summary>
+    [PseudoClasses(":error", ":information", ":success", ":warning")]
     public class NotificationCard : ContentControl
     {
         private bool _isClosed;
diff --git a/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs b/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs
index 6d9f6b8b77..8f5c6faf40 100644
--- a/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs
+++ b/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs
@@ -7,12 +7,14 @@ using Avalonia.Controls.Primitives;
 using Avalonia.Rendering;
 using Avalonia.Data;
 using Avalonia.VisualTree;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls.Notifications
 {
     /// <summary>
     /// An <see cref="INotificationManager"/> that displays notifications in a <see cref="Window"/>.
     /// </summary>
+    [PseudoClasses(":topleft", ":topright", ":bottomleft", ":bottomright")]
     public class WindowNotificationManager : TemplatedControl, IManagedNotificationManager, ICustomSimpleHitTest
     {
         private IList _items;
diff --git a/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs b/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs
index 8c464c7aad..7f1dbdf592 100644
--- a/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs
+++ b/src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs
@@ -221,7 +221,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
 
                 if (!FitsInBounds(unconstrainedRect, PopupAnchor.Bottom))
                 {
-                    unconstrainedRect = unconstrainedRect.WithHeight(bounds.Height - unconstrainedRect.Y);
+                    unconstrainedRect = unconstrainedRect.WithHeight(bounds.Bottom - unconstrainedRect.Y);
                 }
 
                 if (IsValid(unconstrainedRect))
diff --git a/src/Avalonia.Controls/Primitives/ScrollBar.cs b/src/Avalonia.Controls/Primitives/ScrollBar.cs
index 477d24dc99..a7fb7ae08c 100644
--- a/src/Avalonia.Controls/Primitives/ScrollBar.cs
+++ b/src/Avalonia.Controls/Primitives/ScrollBar.cs
@@ -4,6 +4,7 @@ using Avalonia.Interactivity;
 using Avalonia.Input;
 using Avalonia.Layout;
 using Avalonia.Threading;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls.Primitives
 {
@@ -21,6 +22,7 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// A scrollbar control.
     /// </summary>
+    [PseudoClasses(":vertical", ":horizontal")]
     public class ScrollBar : RangeBase
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Primitives/Thumb.cs b/src/Avalonia.Controls/Primitives/Thumb.cs
index 96810ed01b..348922b71d 100644
--- a/src/Avalonia.Controls/Primitives/Thumb.cs
+++ b/src/Avalonia.Controls/Primitives/Thumb.cs
@@ -1,9 +1,11 @@
 using System;
+using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 
 namespace Avalonia.Controls.Primitives
 {
+    [PseudoClasses(":pressed")]
     public class Thumb : TemplatedControl
     {
         public static readonly RoutedEvent<VectorEventArgs> DragStartedEvent =
diff --git a/src/Avalonia.Controls/Primitives/ToggleButton.cs b/src/Avalonia.Controls/Primitives/ToggleButton.cs
index 13031ddad8..f96ca9310d 100644
--- a/src/Avalonia.Controls/Primitives/ToggleButton.cs
+++ b/src/Avalonia.Controls/Primitives/ToggleButton.cs
@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Interactivity;
 
@@ -7,6 +8,7 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// Represents a control that a user can select (check) or clear (uncheck). Base class for controls that can switch states.
     /// </summary>
+    [PseudoClasses(":checked", ":unchecked", ":indeterminate")]
     public class ToggleButton : Button
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Primitives/Track.cs b/src/Avalonia.Controls/Primitives/Track.cs
index 29e7f28b44..9399f5fb31 100644
--- a/src/Avalonia.Controls/Primitives/Track.cs
+++ b/src/Avalonia.Controls/Primitives/Track.cs
@@ -4,6 +4,7 @@
 // Licensed to The Avalonia Project under MIT License, courtesy of The .NET Foundation.
 
 using System;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Layout;
@@ -12,6 +13,7 @@ using Avalonia.Utilities;
 
 namespace Avalonia.Controls.Primitives
 {
+    [PseudoClasses(":vertical", ":horizontal")]
     public class Track : Control
     {
         public static readonly DirectProperty<Track, double> MinimumProperty =
diff --git a/src/Avalonia.Controls/ProgressBar.cs b/src/Avalonia.Controls/ProgressBar.cs
index a92f24a050..161f09d9b6 100644
--- a/src/Avalonia.Controls/ProgressBar.cs
+++ b/src/Avalonia.Controls/ProgressBar.cs
@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Layout;
 using Avalonia.Media;
@@ -8,6 +9,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control used to indicate the progress of an operation.
     /// </summary>
+    [PseudoClasses(":vertical", ":horizontal", ":indeterminate")]
     public class ProgressBar : RangeBase
     {
         public class ProgressBarTemplateProperties : AvaloniaObject
diff --git a/src/Avalonia.Controls/Slider.cs b/src/Avalonia.Controls/Slider.cs
index 293cbac82f..6e08e78813 100644
--- a/src/Avalonia.Controls/Slider.cs
+++ b/src/Avalonia.Controls/Slider.cs
@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Collections;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
@@ -39,6 +40,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control that lets the user select from a range of values by moving a Thumb control along a Track.
     /// </summary>
+    [PseudoClasses(":vertical", ":horizontal", ":pressed")]
     public class Slider : RangeBase
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/SplitView.cs b/src/Avalonia.Controls/SplitView.cs
index b71858f796..8267efc466 100644
--- a/src/Avalonia.Controls/SplitView.cs
+++ b/src/Avalonia.Controls/SplitView.cs
@@ -1,4 +1,5 @@
-using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Input.Raw;
 using Avalonia.Interactivity;
@@ -73,6 +74,10 @@ namespace Avalonia.Controls
     /// <summary>
     /// A control with two views: A collapsible pane and an area for content
     /// </summary>
+    [PseudoClasses(":open", ":closed")]
+    [PseudoClasses(":compactoverlay", ":compactinline", ":overlay", ":inline")]
+    [PseudoClasses(":left", ":right")]
+    [PseudoClasses(":lightdismiss")]
     public class SplitView : TemplatedControl
     {
         /*
diff --git a/src/Avalonia.Controls/TabItem.cs b/src/Avalonia.Controls/TabItem.cs
index 6320443a13..593643a1eb 100644
--- a/src/Avalonia.Controls/TabItem.cs
+++ b/src/Avalonia.Controls/TabItem.cs
@@ -1,3 +1,4 @@
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 
@@ -6,6 +7,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// An item in  a <see cref="TabStrip"/> or <see cref="TabControl"/>.
     /// </summary>
+    [PseudoClasses(":pressed", ":selected")]
     public class TabItem : HeaderedContentControl, ISelectable
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/TextBox.cs b/src/Avalonia.Controls/TextBox.cs
index 73a1ae3335..0fe3ac62e4 100644
--- a/src/Avalonia.Controls/TextBox.cs
+++ b/src/Avalonia.Controls/TextBox.cs
@@ -13,9 +13,11 @@ using Avalonia.Metadata;
 using Avalonia.Data;
 using Avalonia.Layout;
 using Avalonia.Utilities;
+using Avalonia.Controls.Metadata;
 
 namespace Avalonia.Controls
 {
+    [PseudoClasses(":empty")]
     public class TextBox : TemplatedControl, UndoRedoHelper<TextBox.UndoRedoState>.IUndoRedoHost
     {
         public static KeyGesture CutGesture { get; } = AvaloniaLocator.Current
diff --git a/src/Avalonia.Controls/ToggleSwitch.cs b/src/Avalonia.Controls/ToggleSwitch.cs
index c32f2d8102..662a355dac 100644
--- a/src/Avalonia.Controls/ToggleSwitch.cs
+++ b/src/Avalonia.Controls/ToggleSwitch.cs
@@ -1,4 +1,5 @@
-using Avalonia.Controls.Presenters;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.LogicalTree;
@@ -8,6 +9,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// A Toggle Switch control.
     /// </summary>
+    [PseudoClasses(":dragging")]
     public class ToggleSwitch : ToggleButton
     {
         private Panel _knobsPanel;
diff --git a/src/Avalonia.Controls/ToolTip.cs b/src/Avalonia.Controls/ToolTip.cs
index d56ff5752f..71bd0726d4 100644
--- a/src/Avalonia.Controls/ToolTip.cs
+++ b/src/Avalonia.Controls/ToolTip.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Reactive.Linq;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.VisualTree;
 
@@ -14,6 +15,7 @@ namespace Avalonia.Controls
     /// To add a tooltip to a control, use the <see cref="TipProperty"/> attached property,
     /// assigning the content that you want displayed.
     /// </remarks>
+    [PseudoClasses(":open")]
     public class ToolTip : ContentControl
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/TreeViewItem.cs b/src/Avalonia.Controls/TreeViewItem.cs
index 4942d4d313..8ce258b546 100644
--- a/src/Avalonia.Controls/TreeViewItem.cs
+++ b/src/Avalonia.Controls/TreeViewItem.cs
@@ -1,5 +1,6 @@
 using System.Linq;
 using Avalonia.Controls.Generators;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
@@ -11,6 +12,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// An item in a <see cref="TreeView"/>.
     /// </summary>
+    [PseudoClasses(":pressed", ":selected")]
     public class TreeViewItem : HeaderedItemsControl, ISelectable
     {
         /// <summary>
diff --git a/src/Avalonia.Input/InputElement.cs b/src/Avalonia.Input/InputElement.cs
index 25f2d553d7..9ace7fd92d 100644
--- a/src/Avalonia.Input/InputElement.cs
+++ b/src/Avalonia.Input/InputElement.cs
@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using Avalonia.Controls;
+using Avalonia.Controls.Metadata;
 using Avalonia.Data;
 using Avalonia.Input.GestureRecognizers;
 using Avalonia.Interactivity;
@@ -12,6 +13,7 @@ namespace Avalonia.Input
     /// <summary>
     /// Implements input-related functionality for a control.
     /// </summary>
+    [PseudoClasses(":disabled", ":focus", ":focus-visible", ":pointerover")]
     public class InputElement : Interactive, IInputElement
     {
         /// <summary>
diff --git a/src/Avalonia.Styling/Controls/Metadata/PseudoClassesAttribute.cs b/src/Avalonia.Styling/Controls/Metadata/PseudoClassesAttribute.cs
new file mode 100644
index 0000000000..0060767565
--- /dev/null
+++ b/src/Avalonia.Styling/Controls/Metadata/PseudoClassesAttribute.cs
@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+
+#nullable enable
+
+namespace Avalonia.Controls.Metadata
+{
+    [AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
+    public sealed class PseudoClassesAttribute : Attribute
+    {
+        public PseudoClassesAttribute(params string[] pseudoClasses)
+        {
+            PseudoClasses = pseudoClasses;
+        }
+
+        public IReadOnlyList<string> PseudoClasses { get; }
+    }
+}
diff --git a/src/Avalonia.Themes.Fluent/Button.xaml b/src/Avalonia.Themes.Fluent/Button.xaml
index e58e8758d2..8522c933ae 100644
--- a/src/Avalonia.Themes.Fluent/Button.xaml
+++ b/src/Avalonia.Themes.Fluent/Button.xaml
@@ -77,7 +77,7 @@
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource AccentButtonForegroundPressed}" />
   </Style>
 
-  <Style Selector="Button">
+  <Style Selector="Button, RepeatButton, ToggleButton">
     <Setter Property="RenderTransform" Value="none" />
     <Setter Property="Transitions">
       <Transitions>
@@ -86,7 +86,7 @@
     </Setter>
   </Style>
 
-  <Style Selector="Button:pressed">
+  <Style Selector="Button:pressed, RepeatButton:pressed, ToggleButton:pressed">
     <Setter Property="RenderTransform" Value="scale(0.98)" />    
   </Style>
 
diff --git a/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs b/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs
index 57cea91834..3e78e951e2 100644
--- a/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/AutoCompleteBoxTests.cs
@@ -363,6 +363,40 @@ namespace Avalonia.Controls.UnitTests
             });
         }
         
+        [Fact]
+        public void Custom_TextSelector()
+        {
+            RunTest((control, textbox) =>
+            {
+                object selectedItem = control.Items.Cast<object>().First();
+                string input = "42";
+
+                control.TextSelector = (text, item) => text + item;
+                Assert.Equal(control.TextSelector("4", "2"), "42");
+
+                control.Text = input;
+                control.SelectedItem = selectedItem;
+                Assert.Equal(control.Text, control.TextSelector(input, selectedItem.ToString()));
+            });
+        }
+        
+        [Fact]
+        public void Custom_ItemSelector()
+        {
+            RunTest((control, textbox) =>
+            {
+                object selectedItem = control.Items.Cast<object>().First();
+                string input = "42";
+
+                control.ItemSelector = (text, item) => text + item;
+                Assert.Equal(control.ItemSelector("4", 2), "42");
+
+                control.Text = input;
+                control.SelectedItem = selectedItem;
+                Assert.Equal(control.Text, control.ItemSelector(input, selectedItem));
+            });
+        }
+
         /// <summary>
         /// Retrieves a defined predicate filter through a new AutoCompleteBox 
         /// control instance.