ComboBox: add focusvisual pseudoclass to replace focus adorner

src/Avalonia.Controls/ComboBox.cs

@@ -262,6 +262,21 @@ namespace Avalonia.Controls
             _popup.Closed += PopupClosed;
         }
 
+        protected override void OnGotFocus(GotFocusEventArgs e)
+        {
+            if (e.NavigationMethod == NavigationMethod.Tab
+                || e.NavigationMethod == NavigationMethod.Directional)
+            {
+                PseudoClasses.Set(":focusvisual", true);
+            }
+        }
+
+        protected override void OnLostFocus(RoutedEventArgs e)
+        {
+            base.OnLostFocus(e);
+            PseudoClasses.Set(":focusvisual", false);
+        }
+
         /// <summary>
         /// Called when the ComboBox popup is closed, with the <see cref="PopupClosedEventArgs"/>
         /// that caused the popup to close.

src/Avalonia.Themes.Fluent/ComboBox.xaml

@@ -191,20 +191,20 @@
   </Style>
 
   <!--  Focused State  -->
-  <Style Selector="ComboBox:focus /template/ Border#HighlightBackground">
+  <Style Selector="ComboBox:focusvisual /template/ Border#HighlightBackground">
     <Setter Property="IsVisible" Value="True" />
     <Setter Property="BorderBrush" Value="{DynamicResource ComboBoxBackgroundBorderBrushFocused}" />
   </Style>
 
-  <Style Selector="ComboBox:focus /template/ ContentControl#ContentPresenter">
+  <Style Selector="ComboBox:focusvisual /template/ ContentControl#ContentPresenter">
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource ComboBoxForegroundFocused}" />
   </Style>
 
-  <Style Selector="ComboBox:focus /template/ TextBlock#PlaceholderTextBlock">
+  <Style Selector="ComboBox:focusvisual /template/ TextBlock#PlaceholderTextBlock">
     <Setter Property="TextBlock.Foreground" Value="{Binding PlaceholderForeground, RelativeSource={RelativeSource TemplatedParent}, TargetNullValue={DynamicResource ComboBoxForegroundFocused}}" />
   </Style>
 
-  <Style Selector="ComboBox:focus /template/ Path#DropDownGlyph">
+  <Style Selector="ComboBox:focusvisual /template/ Path#DropDownGlyph">
     <Setter Property="Fill" Value="{DynamicResource ComboBoxDropDownGlyphForegroundFocused}" />
   </Style>