<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="Microsoft.Samples.Graphics.RectangleExample" WindowTitle="Example"> <Canvas> <Button Background="Purple" FontSize="14" FontWeight="Bold"> <Button.OpacityMask> <LinearGradientBrush StartPoint="0,0" EndPoint="1,0"> <GradientStop Offset="0" Color="Black"></GradientStop> <GradientStop Offset="1" Color="Transparent"></GradientStop> </LinearGradientBrush> </Button.OpacityMask> <Button.Content>A Partially Transparent Button</Button.Content> </Button> </Canvas> </Page>