Hi, 
I just have installed wpf q1 2011 trial version, and after I convert my project I noticed that horizontal alignment for some controls are not working (rad expander, border). They just don't respond to changing alignment, it is impossibly to stretch control inside some container(grid or border)...
Do You know something about  this strange behavior?
Nebojsa Danilovic

Hi Nebojsa Danilovic,

Please accept our apologies for the caused inconvenience. During the last Q the Expander control went under extensive changes. Our goal was to improve the performance of the control and fix many of the bugs. Unfortunately we have introduced an issue related to the Alignment properties, which is already fixed and you should be able to download it with our next internal build.

In the meantime I attached a sample project where the default style of the RadExpander is modified to allow stretching. Please give it a try and let us know if it works for you.

All the best,
Tina Stancheva
the Telerik team