[regression] Window management - Middle clicking panel no longer focuses window behind it

I bind Alt-F3 to Lower window. When pressing the shortcut the window is lowered but it retains focus. I have to press Alt-F3 twice to switch focus from the lowered window

This is 12.10 as of August 23, 2012 at 14:00 UTC.

How to repeat:
   gsettings set org.gnome.desktop.wm.keybindings lower "['<Alt>f3']"
   # press Alt+F3

What happened:
   The window is lowered but keeps focus

What should happen:
   The next window in the stack should get focus.

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The autopilot test:
unity.tests.test_panel.PanelGrabAreaTests.test_lower_the_maximized_window_works

Is failing.

What should happen:
1) Open gnome-calculator
2) Open gedit, and maximize it
3) Middle click the Panel

Expected:
Gedit should fall behind the calculator and the calculator should get focus

What happens:
Gedit falls behind the calculator, but gedit keeps focus.

NEEDS-DESIGN: Upon middle-clicking panel, should the last used window get focus too?
ANSWER FROM DESIGN: When a window is sent to the back, the last used window should get focus (the testcase and expected results described above are correct)