I have got similar problem. But I´m opening RadWindow from UserControl, so can´t set owner to UserControl. Is there another way how to set RadWindow opened from UserControl always on the top? I tried to set owner to RadRibbonMainWindow, but that doesn´t work.
public partial class App : Application
// user control
MainWindow MainWindow = Administration2010.MainWindow.Instance;
RadRibbonMainWindow ribbonWindow = Administration2010.RadRibbonMainWindow.Instance;
ribbonWindow.Content = MainWindow;
EDIT: I´m sorry, that works to set Owner at RadRibbonMainWindow. I did something wrong.