List corruption in win32k triggered at shutdown.

To reproduce:
1- open notepad
2- write some text, but do not save
3- shutdown ReactOS (via start menu for example)
4- when notepad asks for saving file, don't do anything and wait..
5- ... until the "terminate program" dialog pops up. Click on "terminate program" button to force it to close.
6- ...
.... enjoy!! (see the log for more details).

Cc'ed to thephysicist and jimtabor