sorry, this is kinda weird to describe and explain. so please bear with me and be patient 
Designer, 7910
working on a main window …
I have a Power Table and a List,
at some point I displayed the Power Table Dataset Viewer …
it’s difficult to reproduce so I cannot tell you what I did to get there but at some point, I can only see that this popup only seems to appear if I click on the Windows Taskbar like this…
and the only way to get rid of it will be to close the Designer …
it’s more an “annoying” cosmetic error than a real showstopper but I figure it would be interesting to share