Window level resource

   
       

<Window x:Class="Resources.WindowResource"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Resources" Height="300" Width="300"
    >
  <Window.Resources>
    <ImageBrush x:Key="TileBrush" TileMode="Tile"
                ViewportUnits="Absolute" Viewport="0 0 32 32"
                ImageSource="happyface.jpg" Opacity="0.3"></ImageBrush>
  </Window.Resources>
    <StackPanel Margin="5">
      <Button Background="{StaticResource TileBrush}" Padding="5"
              FontWeight="Bold" FontSize="14" Margin="5"
              >A Tiled Button</Button>
    </StackPanel>
</Window>