Applies a vertical skew of 45 degrees from a center point of (25,25)

   
  

<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="25" CenterY="25" AngleX="0" AngleY="45" />
            </Rectangle.RenderTransform>
          </Rectangle> 
        </Canvas>

</Window>