Sorry to follow up (late) to your first email.
Regarding functionality, I've looked at geanyprj and gproject, and neither do what I'm thinking exactly :
gproject : The files are viewed in a nice tree, however that tree reflects the disk layout, rather than functional groups. And attempting to pull in just a few files would result in an ultra-ugly 'filter'.
geanyprj : (With autofill files off) Looks promising, except that list of user-chosen files is just linear. Perhaps this would be the easier one to pop a tree-view into, and still have it loading existing project files in a compatible way
djynn : This looks very promising, however, the author made a breaking change in the source tree last year, and (even though I've now got a version that compiles cleanly) there are some seg-faulting issues that make it too difficult to put through its paces enough to see. It also appears to be pretty unwelcoming code-wise.
So: As it stands, enhancing geanyprj seems like it could be decent approach. Or forking it, since it's overview makes it sound as if its purpose is to dip into lots of projects/codebases, rather than enable good organization of a single project (and context changes, if opened in a different base directory)
Hope this makes sense
Martin
:-)
PS: But doing this in Python is a lot more appealing than C... But I can see the packaging issues may outweigh the convenience.