Created attachment 48707 [details]
Window X's window menu and artefact in Window Y

Version:           unspecified (using Devel) 
OS:                Linux

Only happens with compositing off. This doesn't seem to be limited to menus, but can also happen with Plasma's tool tips. I'm trying to find a pattern, but every time I think I've found something, after some more testing it seems it doesn't always apply.

Reproducible: Sometimes

Steps to Reproduce:
1. Turn compositing off
2. Open two windows
3. Click the first window's window icon. The menu opens.
3. Do the same on the second window. In the first window, a transparent area of same size and position as the first window's menu will appear. Though I don't know if the areas are always the same that were used to show menus earlier in the first window, as if navigating the window menu's submenus, it sometimes does show transparent areas for them, sometimes not.

Also works with Plasma's tooltips:
1. Have for example clock and system tray on the panel.
2. Open a window so that the clock's tooltip will be over the window.
3. Hover the clock so that its tooltip will appear.
4. Move the mouse off the panel, and then hover for example kmix in system tray
5. Its tooltip will appear and a transparent area of same size and position as the clock's tooltip was will appear on the opened window, showing the content behind the window (not always the desktop).

I'm still not sure if this behavior happens always or just sometimes.


Expected Results:  
No artefacts.

Happens with both NVidia's proprietary drivers and open source drivers for ATI. Also in Arch Linux with latest updates and Kubuntu 10.04 LTS without any updates/backports. Screenshots are from 4.4.5, but happens with 4.5 from SVN (checked out a few days ago).