After updating to KDE 4.9.1 I've started getting "stuck" windows. Today I got to my computer, entered the password to unlock it and it unlocked fine but the window asking for the password was kept on screen. Background image showed fine, applications worked fine, except the unlock window was in front of them all.

Cursor was responding to window underneath, not to the stuck window. Tried "xkill" on the stuck window but the window underneath was killed. Only way I got it to disappear was restarting X with Ctrl-Alt-Bcksp

Later it happened again, this time with a window asking for the root password (i was changing some clock settings). "xkill" doesn't work on it and it's only displaying on it's original desktop (and not on all six virtual desktops). This window isn't always on top and as such doesn't really bother me so I haven't restarted X so as to able to extract information from the system.

Another curious thing is that this second window actually goes down the window stack like a normal window. It started on top, then when i changed to a second window it went behind that window, not to the bottom. It appears to work like a window that is "transparent" to input events.

Marked it with Major severity because if the window is an always-on-top it makes using the desktop very very hard.

Reproducible: Couldn't Reproduce

Steps to Reproduce:
No idea....