TranslateTransform X: 50 / Y: 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>
              <TranslateTransform X="50" Y="0" />
            </Rectangle.RenderTransform>
          </Rectangle>
          <Rectangle Style="{StaticResource MarkerRectangleStyle}"  />            
        </Canvas>

</Window>