This sample demonstrates a simple way for a control to do template switching based on the ActualWidth range value of the Window the control is hosted in.

For this sample app to work correctly you must have the blendables Essentials Mix installed.

You can build this application using VisualStudio or Expression Blend.

When the app runs you will see a large blue ellipse. Resize the window to see the blue ellipse switch to a red rectangle.

For detailed instructions on this sample please seen Nathan's post on designerslove.net: http://designerslove.net/?p=80

*Remember you MUST add the IdentityMine.Windows.dll and IdentityMine.Windows.Essentials.dll reference assemblies to the samples before running them.  They can be found at %ProgramFiles%\Reference Assemblies\IdentityMine Blendables\Essentials Mix\v1.0 once you install the CTP. 

originally posted by Nathan Dunlap