Applies a horizontal skew of 45 degrees from a center point of (0,0)

   
  
<Window x:Class="Workspace.DockExample"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Workspace" Width="640" Height="480">
        <Canvas Width="250" Height="250">
          <Rectangle 
            Height="50" Width="50" Fill="#CCCCCCFF" 
            Stroke="Blue" StrokeThickness="2"
            Canvas.Left="100" Canvas.Top="100">
            <Rectangle.RenderTransform>
              <SkewTransform CenterX="0" CenterY="0" AngleX="45" AngleY="0" />
            </Rectangle.RenderTransform>
          </Rectangle>
        </Canvas>

</Window>