This is the correct way to have RadWindow always maximized. However it appears that there is issue causing the described behavior which has already been logged in our P.I.T.S. system. You can track its status on the link below:
I updated your Telerik points for bringing this to our attention.
TRY TELERIK'S NEWEST PRODUCT - EQATEC APPLICATION ANALYTICS for SILVERLIGHT.
Learn what features your users use (or don't use) in your application. Know your audience. Target it better. Develop wisely.
Sign up for Free application insights >>