fluent 2 - fix combo box scale transition

src/Avalonia.Themes.Fluent2/Controls/ComboBoxItem.xaml

@@ -1,5 +1,6 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    xmlns:sys="using:System"
                     x:ClassModifier="internal">
   <Design.PreviewWith>
     <Border Padding="20">
@@ -23,7 +24,8 @@
   <CornerRadius x:Key="ComboBoxItemCornerRadius">3</CornerRadius>
   <x:Double x:Key="ComboBoxItemPillWidth">3</x:Double>
   <x:Double x:Key="ComboBoxItemPillHeight">16</x:Double>
-  <x:Double x:Key="ComboBoxItemPillMinScale">0.625</x:Double>
+  <x:Double x:Key="ComboBoxItemPillScaledHeight">10</x:Double>
+  <sys:TimeSpan x:Key="ComboBoxItemScaleAnimationDuration">00:00:00.167</sys:TimeSpan>
 
   <ControlTheme TargetType="Rectangle" x:Key="ComboBoxItemPill">
     <Setter Property="HorizontalAlignment" Value="Left" />
@@ -58,7 +60,15 @@
                        Opacity="0"
                        IsHitTestVisible="False"
                        UseLayoutRounding="False"
-                       RenderTransform="scaleY(1)"/>
+                       RenderTransform="scaleY(1)">
+              <Rectangle.Transitions>
+                <Transitions>
+                  <DoubleTransition Property="Height"
+                                                 Duration="{DynamicResource ComboBoxItemScaleAnimationDuration}"
+                                                 Easing="0,0,0,1"/>
+                </Transitions>
+              </Rectangle.Transitions>
+            </Rectangle>
             <ContentPresenter Name="PART_ContentPresenter"
                               Foreground="{TemplateBinding Foreground}"
                               BackgroundSizing="InnerBorderEdge"
@@ -149,9 +159,7 @@
         <Setter Property="Foreground" Value="{DynamicResource ComboBoxItemForegroundSelectedPressed}" />
       </Style>
       <Style Selector="^:pressed /template/ Rectangle#Pill">
-        <Setter Property="RenderTransform" >
-          <ScaleTransform ScaleY="{DynamicResource ComboBoxItemPillMinScale}" />
-        </Setter>
+        <Setter Property="Height" Value="{DynamicResource ComboBoxItemPillScaledHeight}"/>
       </Style>
     </Style>
   </ControlTheme>