Quote:
.. am i missing something?
Yes, The flatpak Gimp is essentially sandboxed and runs in its own space. Self-contained and does not use existing files.
Generally scripts and python plugins will work but some compiled plugins that have certain dependencies will fail. It is possible to do a little gentle hacking and get some working.
This is my report when starting to use a flatpak, kubuntu 16.04 so same base as Mint 18.
https://www.gimp-forum.net/Thread-ubunt ... 41#pid7741If you are able to copy files as root then you will get Gmic GTK working. The QT version runs into conflicts. I have updated the zipped archive you can find from above recently, so gmic looks like this. (Lyles latest wish fulfilled)

I am sure that someone will be along to suggest using an appimage, the choice is yours.