Hello again,
I managed to modify the geany sources so txt2tags is partially supported: The tagmanager is rather ok, and syntax highlight is beginning to work.
I'd like to submit this work to the geany developpers, what is the best practice to do so: for example uploading the modified sources somewhere on my website so you can grab them, review them and eventually integrate them? Is there a better way? I can use svn if needed (for working on a branch)