Merge pull request #9398 from harshit7962/partTemplateParity

Adding Part_ Template parity

Author: harshit7962

src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/ComboBox.xaml

@@ -266,7 +266,7 @@
                                     </Grid>
                                 </Grid>
                                 <Popup
-                                    x:Name="Popup"
+                                    x:Name="PART_Popup"
                                     MinWidth="{TemplateBinding ActualWidth}"
                                     VerticalAlignment="Center"
                                     AllowsTransparency="True"
@@ -357,7 +357,7 @@
                         <Trigger Property="HasItems" Value="False">
                             <Setter TargetName="DropDownBorder" Property="MinHeight" Value="{StaticResource ComboBoxPopupMinHeight}" />
                         </Trigger>
-                        <Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="False">
+                        <Trigger SourceName="PART_Popup" Property="Popup.AllowsTransparency" Value="False">
                             <Setter TargetName="DropDownBorder" Property="CornerRadius" Value="0" />
                         </Trigger>
                         <Trigger Property="IsGrouping" Value="True">

src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/DatePicker.xaml

@@ -46,9 +46,34 @@
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="{x:Type DatePickerTextBox}">
-                    <Border Margin="{TemplateBinding Margin}">
-                        <Decorator x:Name="PART_ContentHost" Margin="{TemplateBinding Padding}" />
-                    </Border>
+                    <Grid>
+                        <VisualStateManager.VisualStateGroups>
+                            <VisualStateGroup Name="WatermarkStates">
+                                <VisualStateGroup.Transitions>
+                                    <VisualTransition GeneratedDuration="0" />
+                                </VisualStateGroup.Transitions>
+                                <VisualState Name="Unwatermarked" />
+                                <VisualState Name="Watermarked">
+                                    <Storyboard>
+                                        <DoubleAnimation Storyboard.TargetName="PART_Watermark" Storyboard.TargetProperty="Opacity" To="1" Duration="0" />
+                                    </Storyboard>
+                                </VisualState>
+                            </VisualStateGroup>
+                        </VisualStateManager.VisualStateGroups>
+                        
+                        <Border Margin="{TemplateBinding Margin}">
+                            <Decorator x:Name="PART_ContentHost" Margin="{TemplateBinding Padding}" />
+                        </Border>
+                        <Border Margin="{TemplateBinding Margin}">
+                            <!-- This is a placeholder for DatePickerTextBox -->
+                            <ContentControl 
+                                x:Name="PART_Watermark"
+                                Opacity="0"
+                                Margin="{TemplateBinding Padding}"
+                                Focusable="False"
+                                IsHitTestVisible="False" />
+                        </Border>
+                    </Grid>
                 </ControlTemplate>
             </Setter.Value>
         </Setter>
@@ -104,7 +129,7 @@
                                 BorderBrush="{TemplateBinding BorderBrush}"
                                 BorderThickness="{TemplateBinding BorderThickness}"
                                 CornerRadius="{TemplateBinding Border.CornerRadius}">
-                                <Grid FocusManager.FocusedElement="{Binding ElementName=PART_Button}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
+                                <Grid x:Name="PART_Root" FocusManager.FocusedElement="{Binding ElementName=PART_Button}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
                                     <Grid.ColumnDefinitions>
                                         <ColumnDefinition Width="*" />
                                         <ColumnDefinition Width="Auto" />

src/Microsoft.DotNet.Wpf/src/Themes/PresentationFramework.Fluent/Styles/MenuItem.xaml

@@ -75,7 +75,7 @@
                 </Grid>
 
                 <Popup
-                    x:Name="Popup"
+                    x:Name="PART_Popup"
                     Grid.Row="1"
                     Grid.Column="0"
                     AllowsTransparency="True"
@@ -334,7 +334,7 @@
             </Border>
 
             <Popup
-                x:Name="Popup"
+                x:Name="PART_Popup"
                 Grid.Row="1"
                 AllowsTransparency="True"
                 Focusable="False"