[TriLUG] Bleeding-edge Kernel + Xorg + Xinerama + Nouveau == can't lock screen

[Brian]

Hi Folks,

I've just loaded the latest Debian Stable on an aging dual-GPU machine. 
  Both gfx cards are older NVIDIA GeForce cards.  Newer proprietary 
drivers don't support either card, plus proprietary is bad, so I'm going 
with nouveau.

In order to get nouveau working smoothly, I had to update to kernel 3.3 
(to get kernel mode switching), and update to Xorg 1.9.3 (because 
nouveau wants 1.8 or later).

I'm no expert at this, and the end result is:

- Xinerama works.  I've got my gdm3 desktop spanning both screens.
- Keyboard keyrepeat in X got broken somewhere along the way (hugely 
annoying but not the point of this message)
- Lock Screen doesn't work.  Neither the hotkey nor selecting Lock 
Screen from the System menu does anything.

Also, screen savers only display on one screen.  Several years ago I had 
a working Xinerama setup where locking worked and screen savers spanned 
both screens.

Screen locking works with Xinerama off, but it's pretty annoying not 
being able to drag windows between screens.

Anyway, anyone else on the bleeding edge encountered anything similar? 
Any advice to offer?

Many thanks,
~Brian