[xmonad] ManageHelpers: isDialog

Rox [http://rox.sourceforge.net] doesn't use WM_TRANSIENT_FOR for its dialogs, so xmonad treats them as ordinal windows. So I wrote the Query 'isDialog' (which may be useful in other circumstances, too) and added it to XMonad.Hooks.ManageHelpers. After adding 'isDialog --> doCenterFloat' to the manage hook, xmonad shows rox dialogs as floating windows. This is only a poor workaround: When such dialogs are closed, the focus does not go back to the parent window (how should it, xmonad does not know, which window it is). Of course hacking rox would be the better solution. -Johann