Maybe this relates to the bug first described by #1538111. It seems unrelated (all windows closing sometimes) but someone found out that the windows are still open, yet hidden behind the dekstop background window.
So this matches almost the situation when the dekstop icons appear in front. I just don't encounter the hidden windows because I do not use a background image I guess (just set a solid color).
Maybe this relates to the bug first described by #1538111. It seems unrelated (all windows closing sometimes) but someone found out that the windows are still open, yet hidden behind the dekstop background window.
So this matches almost the situation when the dekstop icons appear in front. I just don't encounter the hidden windows because I do not use a background image I guess (just set a solid color).