OK, that was my error. I had removed the dev package late last night. I reinstalled it, and the current build of G'MIC 1.6.2.0 [pre-release #032115] works. You got it.

Ah, finally some good news
Thanks again for your bug report!

It was good to read the thread to the end. And it had a great happy end hehe.
Anyway, the thing because I write is, you should run testing on desktop you use daily. Stable is really only for servers. (Unstable is for Debian devs.) And I even know sysadmins who run testing on production servers lol.

Personally, I would never run full testing on my production machine, except maybe in a VM. If I really needed a new version of something, I might grab it from the testing repos but other than that, I'll stick with stable repos. Maybe it's just me, but I don't have time to be a Fedora "tester" and much prefer working apps over broken ones.

Offtopic:

Who told you? Stable is fine for desktop usage, especially when you don't need the newest version of everything but a very easy to maintain and very safe and reliable system (best choice for people who don't want to deal with the internals of the system, just use it, and don't want to deal with updates too often). There are even other desktop oriented distributions based on it (LMDE will migrate from testing to stable, SolydXK too, Kanotix uses Debian Stable,...). And there also are other very stable desktop distributions using Debian Sid, like siduction (my productive system since years). With a little brain usage Debian Sid can be more reliable than Ubuntu . I'd rather say either use Stable or Unstable - but not Testing. The packages in Testing sometimes just don't work that well or well together as in Stable or Unstable.