http://bugs.winehq.org/show_bug.cgi?id=13177
--- Comment #10 from Andrew O. Shadoura (I DO NOT USE COMPIZ) bugzilla@tut.by 2008-05-22 09:30:17 --- I've found it!
When Miranda IM has 'Become idle if the computer is locked (2000/XP+ only)' option enabled, approximately every second or two I get fixme message:
fixme:win:SwitchDesktop SwitchDesktop(hwnd 0xd8) stub!
And while Miranda is running with such option, shadow is drawn above popup in winhelp. Don't understand yet how this can be, but at least we know what causes this effect.