Created attachment 102948 [details] (Video example) (Krita 3.1.1 on Ubuntu 14.04) When I close the last open document, the main panel (where is displayed the canvas) is not refreshed. Video example in attachment.
Um... I tried, but with 16.10 and couldn't reproduce. I think it might be time to update your Ubuntu?
Yes, I can reproduce it with AppImage + Ubuntu Unity 16.04-pre + NVidia GPU
I cannot confirm it on Ubuntu Unity 16.10 (in a VM), OpenSuse, OSX or Windows.
This definitely is a unity bug, and seems fixed in 16.10. QML-based apps have had a similar problem with unithy for a long time.