SUMMARY I don't know how to reproduce - I think it is always there but I don't always notice. A small undecorated text field, big enough for 2-3 characters hovers over the rest of the kmail window. It is fixed in position relative to the top left corner of the window. current it contains "S '", when the mouse rolls over the cursor switches to a vertical split adjustment pointer but the mouse has no effect on this glitch. If the window is resized or the panes are scroll the position of the glitch is fixed.
Created attachment 120264 [details] glitch in kmail
Created attachment 120265 [details] glitch with window resized
The glitch itself doesn't seem to cause any bother other than being vaguely in the way but I suppose it shouldn't be there and whatever it is should be fixed... If I restart kmail it is gone but sometime later it just reappears - it's been with me for ages (maybe a year) I can't recall it being associated with anything in particular. Since it is very small I don't think I've noticed it appearing but once it appears it stays. I tend to run long uptimes in case that matters.
Sounds very much like bug#391038 I think...
(In reply to Wolfgang Bauer from comment #4) > Sounds very much like bug#391038 I think... indeed *** This bug has been marked as a duplicate of bug 391038 ***