I just installed gThumb 3.9.1 on two Xubuntu 18.04 machines. One is fine, works great, with the minor exception that the launchers don't find the new icons, so it uses the default "?" instead. (any hints about this are appreciated too).
On the other machine, however, gThumb doesn't display image thumbnails. It will display them if I minimize the window and re-max it. Then they show until I click on a different folder, and they are gone again. Min>Max the window and voilà, they are back, instantly. Both machines have similar setups, but different architectures, so they are not identical.
All other apps that use t-nails are working fine.
I'm scratching my head...
Can anybody help?
Just as FYI:
I purged it and then reinstalled gThumb from the repository - but no difference...