I noticed this bug in 12.04 with normal windows too:
1. Use ccsm to set a slow window open animation.
2. Right click on desktop and select Change Desktop Background.
3. You will see the bottom of the window is missing for a couple of frames during the open animation.
You have to be very observant, because the problem is only visible right at the start of the animation. There's a gap above the bottom border/shadow of the window.
I noticed this bug in 12.04 with normal windows too:
1. Use ccsm to set a slow window open animation.
2. Right click on desktop and select Change Desktop Background.
3. You will see the bottom of the window is missing for a couple of frames during the open animation.
You have to be very observant, because the problem is only visible right at the start of the animation. There's a gap above the bottom border/shadow of the window.