For what-so-ever reason gthumb does not show pictures any more.
It just says 'No image'. I checked the Internet and it seems a common
problem, yet, I found no answer.
Now if I open an image with thunar and choose gthumb for it, then that and
only that image is opened with gthumb. If I close the image gthumb tells
again 'No image' even when there are plenty on that directory.
How to correct?
Just found the answer. In Preferences-Browser enable: Determine image type from content.
Remains the question who is dumb.
Took me some hours to find.