1. If you open RadWindow and press back while it is opening (it is a long time to wait coz of first time JIT) it doesn't handle Back button press. The backkeypress event fires AFTER WindowOpened, so i think it should be handled correctly.
2. If i have custom handler for Backkeypress event that sets Cancel to true than if again i press back while popup is opening i get some strange behavior. If i press back again (after i see this strange behavior) - appbar disappears.
Repro project is on DropBox (for 2nd issue please uncomment line in backkeypress handler in MainPage.xaml).