I still have this issue with Debian testing and Nvidia drivers.
ilya@mefesto:/tmp$ apt-cache policy kde-window-manager
kde-window-manager:
Installed: 4:4.6.5-1
Candidate: 4:4.6.5-1
Version table:
4:4.6.5-2 0
*** 4:4.6.5-1 0
100 /var/lib/dpkg/status
ilya@mefesto:/tmp$ apt-cache policy nvidia-glx
nvidia-glx:
Installed: 275.09.07-5
Candidate: 275.09.07-5
Version table:
275.21-1 0
*** 275.09.07-5 0
100 /var/lib/dpkg/status
ilya@mefesto:/tmp$
Regards, Ilya.