chore: Adjust docs and remove test code

doc/material-migration.md

@@ -17,7 +17,7 @@ Previously, the `PlaceholderText` property acted as a header, displaying in the
 ##### New Behavior
 
 - **PlaceholderText**: Displays inside the TextBox when it's empty. Disappears when text is entered.
-- **Header**: Acts as a label. Animates upwards when the TextBox is focused.
+- **Header**: Acts as a label. Animates upwards when text is entered.
 
 ##### Example
 

src/samples/UWP/Uno.Themes.Samples.Shared/Content/Controls/TextBoxSamplePage.xaml

@@ -10,43 +10,7 @@
 	  mc:Ignorable="d">
 
 	<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
-		<Grid.RowDefinitions>
-			<RowDefinition Height="Auto" />
-			<RowDefinition Height="*" />
-		</Grid.RowDefinitions>
-
-		<StackPanel Spacing="10"
-					HorizontalAlignment="Center"
-					Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
-					Orientation="Vertical">
-			<TextBox Style="{StaticResource MaterialFilledTextBoxStyle}"
-					 x:Name="txtMyTb"
-					 Width="270" />
-			<TextBox Style="{StaticResource MaterialOutlinedTextBoxStyle}"
-					 x:Name="txtMyTb1"
-					 Width="270" />
-			<StackPanel HorizontalAlignment="Center"
-						Orientation="Horizontal">
-				<Button Content="Add Header"
-						Click="AddHeader" />
-				<Button Content="Add Placeholder"
-						Click="AddPlaceholder" />
-				<Button Content="Add Text"
-						Click="AddText" />
-			</StackPanel>
-
-			<StackPanel VerticalAlignment="Center"
-						Orientation="Horizontal">
-				<Button Content="Remove Header"
-						Click="RemoveHeader" />
-				<Button Content="Remove Placeholder"
-						Click="RemovePlaceholder" />
-				<Button Content="Remove Text"
-						Click="RemoveText" />
-			</StackPanel>
-
-		</StackPanel>
-		<sample:SamplePageLayout Grid.Row="1">
+		<sample:SamplePageLayout>
 			<sample:SamplePageLayout.MaterialTemplate>
 				<DataTemplate>
 					<StackPanel>

src/samples/UWP/Uno.Themes.Samples.Shared/Content/Controls/TextBoxSamplePage.xaml.cs

@@ -7,40 +7,4 @@ public TextBoxSamplePage()
 	{
 		this.InitializeComponent();
 	}
-
-	private void AddHeader(object sender, RoutedEventArgs e)
-	{
-		txtMyTb.Header = "Header";
-		txtMyTb1.Header = "Header";
-	}
-
-	private void RemoveHeader(object sender, RoutedEventArgs e)
-	{
-		txtMyTb.Header = null;
-		txtMyTb1.Header = null;
-	}
-
-	private void AddPlaceholder(object sender, RoutedEventArgs e)
-	{
-		txtMyTb.PlaceholderText = "Placeholder";
-		txtMyTb1.PlaceholderText = "Placeholder";
-	}
-
-	private void RemovePlaceholder(object sender, RoutedEventArgs e)
-	{
-		txtMyTb.PlaceholderText = null;
-		txtMyTb1.PlaceholderText = null;
-	}
-
-	private void AddText(object sender, RoutedEventArgs e)
-	{
-		txtMyTb.Text = "Text";
-		txtMyTb1.Text = "Text";
-	}
-
-	private void RemoveText(object sender, RoutedEventArgs e)
-	{
-		txtMyTb.Text = null;
-		txtMyTb1.Text = null;
-	}
 }