Following idea from comment #40, if bug still exists it's enough just to press Ctrl+F7, to push display refresh. But at 2016-09-01 with updated 4.4.0-36-generic kernel and X.org server version 1.18.3 this bug seems fixed after locking/unlocking.
Following idea from comment #40, if bug still exists it's enough just to press Ctrl+F7, to push display refresh.
But at 2016-09-01 with updated 4.4.0-36-generic kernel and X.org server version 1.18.3 this bug seems fixed after locking/unlocking.