feat: add :dropdownopen and :pressed pseudoclass for combobox.

simplify fluent theme combobox default template.
update unit test.

src/Avalonia.Controls/ComboBox.cs

@@ -21,8 +21,11 @@ namespace Avalonia.Controls
     /// A drop-down list control.
     /// </summary>
     [TemplatePart("PART_Popup", typeof(Popup))]
+    [PseudoClasses(pcDropdownOpen, pcPressed)]
     public class ComboBox : SelectingItemsControl
     {
+        public const string pcDropdownOpen = ":dropdownopen";
+        public const string pcPressed = ":pressed";
         /// <summary>
         /// The default value for the <see cref="ItemsControl.ItemsPanel"/> property.
         /// </summary>
@@ -95,6 +98,7 @@ namespace Avalonia.Controls
             SelectedItemProperty.Changed.AddClassHandler<ComboBox>((x, e) => x.SelectedItemChanged(e));
             KeyDownEvent.AddClassHandler<ComboBox>((x, e) => x.OnKeyDown(e), Interactivity.RoutingStrategies.Tunnel);
             IsTextSearchEnabledProperty.OverrideDefaultValue<ComboBox>(true);
+            IsDropDownOpenProperty.Changed.AddClassHandler<ComboBox>((x, e) => x.DropdownChanged(e));
         }
 
         /// <summary>
@@ -267,6 +271,20 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <inheritdoc/>
+        protected override void OnPointerPressed(PointerPressedEventArgs e)
+        {
+            base.OnPointerPressed(e);
+            if(!e.Handled && e.Source is IVisual source)
+            {
+                if (_popup?.IsInsidePopup(source) == true)
+                {
+                    return;
+                }
+            }
+            PseudoClasses.Set(pcPressed, true);
+        }
+
         /// <inheritdoc/>
         protected override void OnPointerReleased(PointerReleasedEventArgs e)
         {
@@ -286,10 +304,12 @@ namespace Avalonia.Controls
                     e.Handled = true;
                 }
             }
-
+            PseudoClasses.Set(pcPressed, false);
             base.OnPointerReleased(e);
+            
         }
 
+
         /// <inheritdoc/>
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
@@ -470,5 +490,11 @@ namespace Avalonia.Controls
                 MoveSelection(NavigationDirection.Previous, WrapSelection);
             }
         }
+
+        private void DropdownChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            bool newValue = e.GetNewValue<bool>();
+            PseudoClasses.Set(pcDropdownOpen, newValue);
+        }
     }
 }

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

@@ -57,17 +57,8 @@
     <Setter Property="Template">
       <ControlTemplate>
         <DataValidationErrors>
-          <Grid RowDefinitions="Auto, *, Auto" ColumnDefinitions="*,32">
-            <ContentPresenter x:Name="HeaderContentPresenter"
-                              Grid.Row="0"
-                              Grid.Column="0"
-                              Grid.ColumnSpan="2"
-                              IsVisible="False"
-                              FontWeight="{DynamicResource ComboBoxHeaderThemeFontWeight}"
-                              Margin="{DynamicResource ComboBoxTopHeaderMargin}"
-                              VerticalAlignment="Top" />
+          <Grid ColumnDefinitions="*,32">
             <Border x:Name="Background"
-                    Grid.Row="1"
                     Grid.Column="0"
                     Grid.ColumnSpan="2"
                     Background="{TemplateBinding Background}"
@@ -76,7 +67,6 @@
                     CornerRadius="{TemplateBinding CornerRadius}"
                     MinWidth="{DynamicResource ComboBoxThemeMinWidth}" />
             <Border x:Name="HighlightBackground"
-                    Grid.Row="1"
                     Grid.Column="0"
                     Grid.ColumnSpan="2"
                     Background="{DynamicResource ComboBoxBackgroundUnfocused}"
@@ -85,7 +75,6 @@
                     CornerRadius="{TemplateBinding CornerRadius}"
                     IsVisible="False"/>
             <TextBlock x:Name="PlaceholderTextBlock"
-                       Grid.Row="1"
                        Grid.Column="0"
                        HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                        VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
@@ -96,14 +85,12 @@
             <ContentControl x:Name="ContentPresenter"
                             Content="{TemplateBinding SelectionBoxItem}"
                             ContentTemplate="{TemplateBinding ItemTemplate}"
-                            Grid.Row="1"
                             Grid.Column="0"
                             Margin="{TemplateBinding Padding}"
                             HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                             VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
 
             <Border x:Name="DropDownOverlay"
-                    Grid.Row="1"
                     Grid.Column="1"
                     Background="Transparent"
                     Margin="0,1,1,1"
@@ -112,7 +99,6 @@
                     HorizontalAlignment="Right" />
 
             <PathIcon x:Name="DropDownGlyph"
-                      Grid.Row="1"
                       Grid.Column="1"
                       UseLayoutRounding="False"
                       IsHitTestVisible="False"
@@ -208,9 +194,6 @@
         <Setter Property="Background" Value="{DynamicResource ComboBoxBackgroundDisabled}" />
         <Setter Property="BorderBrush" Value="{DynamicResource ComboBoxBorderBrushDisabled}" />
       </Style>
-      <Style Selector="^ /template/ ContentPresenter#HeaderContentPresenter">
-        <Setter Property="Foreground" Value="{DynamicResource ComboBoxForegroundDisabled}" />
-      </Style>
       <Style Selector="^ /template/ ContentControl#ContentPresenter">
         <Setter Property="Foreground" Value="{DynamicResource ComboBoxForegroundDisabled}" />
       </Style>

tests/Avalonia.Controls.UnitTests/ComboBoxTests.cs

@@ -29,11 +29,36 @@ namespace Avalonia.Controls.UnitTests
             _helper.Down(target);
             _helper.Up(target);
             Assert.True(target.IsDropDownOpen);
+            Assert.True(target.Classes.Contains(ComboBox.pcDropdownOpen));
 
             _helper.Down(target);
             _helper.Up(target);
 
             Assert.False(target.IsDropDownOpen);
+            Assert.True(!target.Classes.Contains(ComboBox.pcDropdownOpen));
+        }
+
+        [Fact]
+        public void Clicking_On_Control_PseudoClass()
+        {
+            var target = new ComboBox
+            {
+                Items = new[] { "Foo", "Bar" },
+            };
+
+            _helper.Down(target);
+            Assert.True(target.Classes.Contains(ComboBox.pcPressed));
+            _helper.Up(target);
+            Assert.True(!target.Classes.Contains(ComboBox.pcPressed));
+            Assert.True(target.Classes.Contains(ComboBox.pcDropdownOpen));
+
+            _helper.Down(target);
+            Assert.True(target.Classes.Contains(ComboBox.pcPressed));
+            _helper.Up(target);
+            Assert.True(!target.Classes.Contains(ComboBox.pcPressed));
+
+            Assert.False(target.IsDropDownOpen);
+            Assert.True(!target.Classes.Contains(ComboBox.pcDropdownOpen));
         }
 
         [Fact]