I experience a very similar bug on oneiric. It happens quite often - every 2 or 3 hours during normal use. I can't give any specific steps to reproduce it but it seems to happen the most when a application with maximized window is started or it's window is minimized or closed. During that time I can't access anything on the current workspace except of unity bars. It looks like something covers a freshly maximized window or desktop when a broken window is minimized. It's is always followed by some graphical distortions (see attached screenshots - on one of them you can see a trail in the left top corner after minimized thunderbird window). Other workspaces are unaffected. Often opening some new window or switching to another workspace and back temporarily fixes this issue.
Using xwinfo reveals that a broken window doesn't get in some way minimized or closed after all! It disappears and it isn't active but somehow blocks everything else on desktop.
This is it's output after minimizing or closing firefox (you can watch it on the movie I've attached):
xwininfo: Window id: 0x281fd16 "Speed Dial - Mozilla Firefox"
I experience a very similar bug on oneiric. It happens quite often - every 2 or 3 hours during normal use. I can't give any specific steps to reproduce it but it seems to happen the most when a application with maximized window is started or it's window is minimized or closed. During that time I can't access anything on the current workspace except of unity bars. It looks like something covers a freshly maximized window or desktop when a broken window is minimized. It's is always followed by some graphical distortions (see attached screenshots - on one of them you can see a trail in the left top corner after minimized thunderbird window). Other workspaces are unaffected. Often opening some new window or switching to another workspace and back temporarily fixes this issue.
Using xwinfo reveals that a broken window doesn't get in some way minimized or closed after all! It disappears and it isn't active but somehow blocks everything else on desktop.
This is it's output after minimizing or closing firefox (you can watch it on the movie I've attached):
xwininfo: Window id: 0x281fd16 "Speed Dial - Mozilla Firefox"
Absolute upper-left X: 0
Absolute upper-left Y: 53
Relative upper-left X: 0
Relative upper-left Y: 0
Width: 1920
Height: 1026
Depth: 24
Visual: 0x21
Visual Class: TrueColor
Border width: 0
Class: InputOutput
Colormap: 0x20 (installed)
Bit Gravity State: NorthWestGravity
Window Gravity State: NorthWestGravity
Backing Store State: NotUseful
Save Under State: no
Map State: IsViewable
Override Redirect State: no
Corners: +0+53 -0+53 -0-1 +0-1
-geometry 1920x1026+0-0