Could it be the 'kill' command ? In kubuntu it is ctrl-alt-esc and if you do not spot the cursor change, a click closes the application window. Although that also gives a Gimp 'eeek' crash / restore message when Gimp is next re-opened.
For a long editing session (any application) you should make regular intermediate saves. I believe automatic backups might come in with Gimp 3 . An old plugin autosave_a.py thrown in as a 'maybe useful'. I have just tried it Gimp 2.10.22 / kubuntu 18.04 including a Gimp 'kill' It is self explanatory when run. Might help.
The usual, unzip, put in ~/.config/GIMP/2.10/plug-ins
History is not saved between sessions even without a crash.
For a long editing session (any application) you should make regular intermediate saves. I believe automatic backups might come in with Gimp 3 . An old plugin autosave_a.py thrown in as a 'maybe useful'. I have just tried it Gimp 2.10.22 / kubuntu 18.04 including a Gimp 'kill' It is self explanatory when run. Might help.
The usual, unzip, put in ~/.config/GIMP/2.10/plug-ins
Quote:When I opened it again, all work was gone and the Undo History was empty
History is not saved between sessions even without a crash.