@Emmanuel
I notice some new, unwanted behaviour.
When I import a model, the icon in the 2D view is shown enlarged 2-3 times its original size. Top-left corner is where it should be, but large part of the rest of the image disappears.

(Under Ubuntu 18.04)

(edit)
Somehow, I get the feeling that the icon problem is connected with the incorrect 3D render in Q1 and Q2 that I mentioned earlier. These also seem to show the top-left part of the "real" image.

Also, when I open Cecilia's "shed" file, or one of my own files, the icons are incorrect. Strange..

I tested this with the Envidia driver recommended for my video card, and with the X-driver that's native to Ubuntu. Both give the same results.

H