Bookworm mtpaint (mtpaint_3.40-3.1+b2_amd64.deb) doesn't support webp file.
I came across this (Barry's post)
https://forum.puppylinux.com/viewtopic. ... 39#p132539
, so with a little googling, I compiled it (v3.50.10).
And that kind of 'resolved' the issue for me.
But.. - I refresh my DOGs iso often. There are few ways to tackle this update.
1. During mklive - overwrite mtpaint with my compiled one.
2. I found that Trixie is using mtpaint (mtpaint_3.50-0.1+b1_amd64.deb). So, I 'could' install the deb with trick that Fred told me (re - deadbeef). But some dependencies to resolve.
3. Beg @fredx181 to update his repo. (Hint..hint...)
Sorry - Off topic. On separate issue - custom actions (right-click).
During this 'exercise', I also found in PCManFM (ObDog, Lxqt-full) can not extract deb files, whereas Thunar (DDOG) can.
Although xarchiver is installed in those (ObDog, Lxqt-full DE). Same error with opening the deb file with xarchiver directly - so may not be FileManager issue (?).
I checked xarchiver version is same in those 3 DE. Who knows (?) - maybe I did something silly (?) like missing a package (?)