https://bugzilla.kernel.org/show_bug.cgi?id=111271
--- Comment #5 from Jean-Yves Faye jean-yves.faye@c-s.fr --- Created attachment 201431 --> https://bugzilla.kernel.org/attachment.cgi?id=201431&action=edit Picture of screen
This was caught on a CRT monitor and is quite visible. The strip follow the mouse cursor on the edge. The white section of screen outside what should be the drawing zone may help you too.