I have setup a LostFocus event on every window that checks the IsActiveWindow property every time the windows loses focus (for debugging purposes). If I have two or more windows and switch between them (by clicking on the border or content) the property correctly gets set to FALSE. However, if the window loses focus to a menu (I use your radmenu) the property stays TRUE (the visual state of the window is unfocused). The problem is that when I click on the header/border of the window afterwards - the GotFocus event is not fired (probably because the IsActiveWindow is TRUE) and the window stays unfocused. I have to click the content area to fire the GotFocus event.