window sent to back retains focus

[positivek]

Using the middle-click on a window's title bar will send it to the back, but the window incorrectly _retains focus_.

Reproduce:
1. Utilize Compiz fusion.
2. Open at least two windows.
3. Use a middle-click on the title bar of the top-most window.

Actual result:
A4. That window sent to the back still maintains focus.

Expected result:
E4. The next most-recently-used (or design-guidelines, best-practices heuristic) window should get focus.

AUX INFO:
The reason to switch focus is that when I send a window to back, I do not want to deal with it anymore (it's in the way). Focus should go to what pre-compiz (or non-compiz) window management does.

See my comment on bug 385047 regarding which window should get focus: "I would argue that the MRU window on the original workspace should get focus, as this will often be the one on top. Remember we must respect the preferences of users who don't use raise_on_click or the use focus under mouse, etc."