ToolWindow allows content to render outside of window bounds when docked

Reproductin steps

Create a WPF application and place the following xaml in the window:

<docking:DockSite
    <docking:SplitContainer>
        <docking:Workspace>
        </docking:Workspace>

        <docking:ToolWindowContainer>
            <docking:ToolWindow x:Name="RedToolWindow" Title="Red Tool Window">
                <Rectangle Fill="Red" RenderTransformOrigin=".5,.5">
                    <Rectangle.RenderTransform>
                        <TranslateTransform X="200"/>
                    </Rectangle.RenderTransform>
                </Rectangle>
            </docking:ToolWindow>
        </docking:ToolWindowContainer>
        <docking:ToolWindowContainer>
            <docking:ToolWindow x:Name="BlueToolWindow" Title="Blue Tool Window">
                <Rectangle Fill="Blue">

                </Rectangle>
            </docking:ToolWindow>
        </docking:ToolWindowContainer>
    </docking:SplitContainer>
</docking:DockSite>

1. Start the application.
2. Undock the blue window and dock to the right of the red window
3. BUG: Notice the red content from the window covers the blue window
4. Undock the red window and dock to the left of the blue window
5. Resize the red window to make it smaller and bigger
6. BUG: Notice the red content does not cover the blue window but does bleed outside of the red window bounds.
7. Undock the red window
8. Notice no red extends past the window bounds