I wouldn't know how vital it is for PellesC's current code, or how easily can be done (or not) but perhaps a separate, dedicated module/function just for function-browsing (the tree) could be a possibly cleaner solution. I mean, disengaging it from other "irrelative" browsing stuff (e.g typedefs, struct members, etc).
But as I said, above, you know better (and I surely trust you!).
Btw, I have to state that in my time I used many C programming environments on several platforms (VMS, BSD Unix, Atari ST's GEM/AES, Macintosh's Finder and DOS/Windows). I find Pelles C the most compatible to my taste, both aesthetically and functionality-wise (I haven't tried VS though, for which I hear only good things).
This is not just a compliment, it's the plain truth! I haven't programmed for more than 10 years and PellesC (which I recently discovered accidentally) was the main reason for trying to remember the programming skills I used to have once upon a time :-)
Now most of my spare time (which unfortunately isn't too much) goes to learning Windows Programming using Pelles C!
(surprisingly, there are too many similarities in programming the now ancient GEM/AES and Windows!)