[nvidia] Blank windows when you Minimize, then Restore with Alt-` (Alt-Grave)

Steps to reproduce, under Unity 3D with the Nvidia proprietary driver (on my machine, GeForce GT 240):

1. Minimize a window, by any means, mouse or keyboard.

2. Restore it with the Alt-` key. You can Alt-Tab through the window spread, Alt-` just needs to be the last key you hit, to activate the window.

3. Repeat if necessary. It does not happen every time, for me, but generally within three tries.

    * Once you have done this, window will show as blank, in the spread.

    * I think for some similar bugs, the window would be blank in the spread, right after being minimized. Not the case, here.

4. Un-maximize the window, and the content will re-appear.

    * Sometimes, it will reappear under other conditions. I don't have a strict definition for this yet. These operations restored the content with other apps, but not with Firefox:

       Minimize again, then restore with Alt-Tab or the mouse. I was able to repeat this with Totem, just now.

       Switch to another window of the same app, then back. I was able to repeat this with EoG.

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Bug 938658 was also about blank windows when restoring from minimized. The conditions were a bit different. To help triage this, here are a couple comments from there -- one by the maintainer, and one from another user confirming this problem.

Didier Roche (didrocks) wrote on 2012-04-24: #54

  @Edward: I suggest that you open another bug report describing exactly the condition for the remaining issues (quite a lot of noise in that bug report). I'll then have a look at it and see if it can be worked for a stable release update :)

Rainer Rohde (rainer-rohde) wrote on 2012-05-02: #57

  In-line with comment #56, I can confirm that the Alt-` (grave accent) window switch produces a blank window several times in a row, while Alt-Tab and maximizing by mouse works just fine.

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DistroRelease: Ubuntu 12.04
Package: unity 5.12-0ubuntu1
NonfreeKernelModules: nvidia
Architecture: amd64