[xmonad] How to get floating focused window on top?

Hello, When dealing with focused windows like dialogs quite often a popup window appears *behind* the main window, stealing the focus. To get access to that window one has to move the main window to get to it. This is quite annoying and it could be easily solved if the focused window where kept on top of the floating windows stack. Is there any way to set this behaviour? Thanks a lot, JP