<Window x:Class="WpfApplication7.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="LinearGradientBrush with OpacityMask" Height="300" Width="300">
<Window.Background>
<LinearGradientBrush>
<GradientStop Offset="0" Color="Red"></GradientStop>
<GradientStop Offset="1" Color="Green"></GradientStop>
</LinearGradientBrush>
</Window.Background>
<Button Margin="40" FontSize="80">RAJ
<Button.OpacityMask>
<LinearGradientBrush EndPoint="0.1,0.1" SpreadMethod="Reflect">
<GradientStop Offset="0" Color="Gray"></GradientStop>
<GradientStop Offset="1" Color="Transparent"></GradientStop>
</LinearGradientBrush>
</Button.OpacityMask>
</Button>
</Window>