I don´t find the way to associate *.mm files with Freeplane copied directly from the zip file from the project’s web page.
Freeplane is not listed in the “Open with…” menu.
It is available in GNOME.

I don´t find the way to associate *.mm files with Freeplane copied directly from the zip file from the project’s web page.
Freeplane is not listed in the “Open with…” menu.
It is available in GNOME.

xdg-mime default freeplane.desktop text/x-objc++src
It works if you install the RPM package from here:
Install package Office / freeplane
Thank you, it worked for me, even without installing the rpms from location you provided. I do have the freeplane.desktop file in
~/.local/share/applications/ directory.
[I corrected the title and the 1st post as I found out that the Freeplane I just copied from the zip file from projects download page Freeplane - Browse /freeplane stable at SourceForge.net and didn’t install it from rpm file. ]