My first screencast. Hope it goes well :) http://www.screencast.com/t/FUdSibQz7H2 If it doesn't work, I've also uploaded it on YouTube: https://www.youtube.com/watch?v=rtoXca2DTgQ
I have tried with other Telerik controls in the background (RadListBox, RadOutlookBar, RadPanelBar, RadTileView, RadToolBar and RadTreeView) and they all work fine. In fact, even RadTileList works if the MouseDoubleClick is made at the RadTileList level instead of the Tile level.
I've just tried with the 'Escape' key to close the RadWindow and that works well too. Another odd way of making it crash is to hit the 'Escape' key after clicking anywhere in the RadWindow (not necessarily clicking the "OK" button).