After reading Patrice's results I got an old (dual core) notebook and installed Xubuntu 20.04 dated April 2021. I installed the ubuntuhandbook ppa Gimp 2.10.30. My last appimage worked fine.
Here are some quick tests I did:
gcc --version = 9.4.0
ldd --version = 2.31
locate stdlib.h = /usr/include/stdlib.h
I've never seen an error message like that one racer-x
![Smile :)](./images/smilies/icon_smile.gif)
Maybe stdlib.h is somewhere else?
I have pretty much moved to Ubuntu 22.04 because developing for an OS that is about to become obsolete is a waste of time IMHO.
Also bundling Gimp in the appimage would be better than figuring out every possible Gimp configuration. Or just do this for myself. I like animating and ways of achieving it.