Dead link. Still have this problem. the offending css is in css file MenuLite.css. It sets z-index to 7000, which is 4000 units higher than the RadWindow I am opening with RadWindow Manager, which is 3002. I DO open the RadWindow with a RadWindowManager located in a user control on the main page, where in fact all the smarts (?) are located, so that control seems to be unable to assert the z-index of its windows to overcome the menu that is defined on the main page (in another user control). The main page consists then of a page with 2 user controls in divs that both have z-10 (Tailwind). Even if I define the window as top etc. and set a z-index in the RWM, no dice. I have to hack the style from MenuLite.css to make it behave.
I expect you will tell me to move the RWM out of the user control to the main page. That is sad.