<Canvas
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  HorizontalAlignment="Center"
  Height="400" Width="400">
    <Canvas Height="400" Width="400" Top="0" Left="0" Background="LightGray"/>
    <Canvas Height="100" Width="100" Top="0" Left="0" Background="Red"/>
    <Canvas Height="100" Width="100" Top="100" Left="100" Background="Green"/>
    <Canvas Height="100" Width="100" Top="50" Left="50" Background="Blue"/>
 </Canvas>
