Port microsoft/microsoft-ui-xaml#3962 (#486)

Author: Kinnara

ModernWpf.Controls/Flyout/FlyoutPresenter.xaml

@@ -15,7 +15,7 @@
         <Setter Property="Foreground" Value="{DynamicResource SystemControlForegroundBaseHighBrush}" />
         <Setter Property="BorderBrush" Value="{DynamicResource FlyoutBorderThemeBrush}" />
         <Setter Property="BorderThickness" Value="{DynamicResource FlyoutBorderThemeThickness}" />
-        <Setter Property="Padding" Value="{DynamicResource FlyoutContentPadding}" />
+        <Setter Property="Padding" Value="{DynamicResource FlyoutContentThemePadding}" />
         <Setter Property="MinWidth" Value="{DynamicResource FlyoutThemeMinWidth}" />
         <Setter Property="MaxWidth" Value="{DynamicResource FlyoutThemeMaxWidth}" />
         <Setter Property="MinHeight" Value="{DynamicResource FlyoutThemeMinHeight}" />

ModernWpf/ControlsResources.xaml

@@ -69,7 +69,6 @@
     <sys:Double x:Key="ToggleSwitchPreContentMargin">6</sys:Double>
     <sys:Double x:Key="ToggleSwitchPostContentMargin">6</sys:Double>
     <sys:Double x:Key="ToggleSwitchThemeMinWidth">154</sys:Double>
-    <Thickness x:Key="FlyoutContentPadding">12</Thickness>
 
     <ControlTemplate x:Key="TextControlValidationErrorTemplate">
         <Grid SnapsToDevicePixels="True">

test/ModernWpfTestApp/CommonStylesPage.xaml

@@ -394,6 +394,18 @@
                         <RadioButton
                             Style="{StaticResource DefaultRadioButtonStyle}"
                             Content="I am a RadioButton with DefaultRadioButtonStyle set" />
+
+                        <ButtonEx Content="Test flyout">
+                            <ButtonEx.Flyout>
+                                <Flyout>
+                                    <StackPanel>
+                                        <TextBlock Style="{DynamicResource BaseTextBlockStyle}" Text="All items will be removed. Do you want to continue?" Margin="0,0,0,12" />
+                                        <Button Content="Yes, empty my cart" />
+                                    </StackPanel>
+                                </Flyout>
+                            </ButtonEx.Flyout>
+                        </ButtonEx>
+                        
                     </StackPanel>
                 </Border>
                 <Border Style="{DynamicResource CompactBorderStyle}">