So it happened to me again today, after not occurring during normal use for some time now. Big white box, caused me to have to restart X to get rid of it.
Interestingly, I discovered that THIS bug seems to be the cause of this bug: #957005
Whenever that large white box is stuck on top of the desktop, I am unable to use the log-out button on the power menu, but ONLY when this bug is occurring.
So it happened to me again today, after not occurring during normal use for some time now. Big white box, caused me to have to restart X to get rid of it.
Interestingly, I discovered that THIS bug seems to be the cause of this bug: #957005
Whenever that large white box is stuck on top of the desktop, I am unable to use the log-out button on the power menu, but ONLY when this bug is occurring.