In Ubuntu 8.10 - Intrepid Ibex:
I have selected the Initiate Window Picker short cut to be just "Super L" (the left Windows button). When pressing it the window picker is not initiated, just "flashed." What I mean is that it doesn't initiate the window picker just briefly enables it. To really use it I must keep the Windows button pressed.
When doing this, the windows behave very erratically. Whenever the mouse is moved, the windows jumps around randomly on the screen, switching positions. This does not always happen, but seems to be reproducible by placing for example two Nautilus windows at the right end of the screen so that they touch the edge. Then initiate the window picker and move the mouse over the windows.
I'm unsure if the bug is in the Keyboard Shortcuts or in Compiz. It could just be that the window picker shouldn't be used like this, that is that it should require the button to be pressed. That's why I didn't select a package.
I have attached a movie of how it looks.
Using compiz on Jaunty Jackalope, I was able to recreate the former part of the bug. Needing to continue to hold keys once the window picker is launched. However, I was not able to recreate the erratic behavior.