I pretty much avoid GIMP now. It became a pity download years ago, but now I'm just not bothering to wait for them to bring the software to the current decade.
Alternatives exist like Photopea, which even with a quarter of the screen covered in ads is way more performant, let alone productive.
Not to blame the maintainers, it seems like they've been left with a mess of spaghetti and no one is willing to help out. I can't say I'm surprised it's taken so long.
Not sure why the downvotes. The good news is that we should be very close to the end of that with GIMP 3 out very soon.
Earlier in the year they announced that it was expected in July or so. I hold out hope that they at least get it out this year. Once it is out, all will be forgieven. Let’s hope that we do not see as long of a delay next time.
I didn't downvote but for a lot of the time the core devs were mostly 1-2 ppl working some evenings because they have dayjobs/lives. They released many updates to 2.10, and they're often feature releases not just bugfix releases. At the same time they almost completely rewrote the backend to use a new graphics library GEGL, which they also wrote from scratch. As for GIMP 3 they have also redone a lot under the hood to allow for easier development of new features moving forward and custom old GTK widgets updating to GTK3 required rearchitecturing as they work fundamentally differently from modern GTK3/4 versions.
So that's why I don't joke, there's also nothing to forgive. Let's hope that GIMP 3 will get more interest from devs with its more modern and capable architecture.
GTK is a UI toolkit, i.e. a piece of software that draws uniform-looking buttons and scrollbars and the like.
GTK used to stand for "GIMP toolkit" but GTK and GIMP development are now entirely separate, so much so, in fact, that 13 years after the release of GTK 3 and 3 years after the release of GTK 4, GIMP still hasn't upgraded to either.
GIMP's GTK3 port was finished several months ago. What remains to be done for GIMP 3.0 is bug-fixing and porting to the new Plug-in API.
The best way to upgrade to GTK4 is to upgrade to GTK3 first. There was some talk about working on GTK4 soon after GIMP 3.0 is out, but whether that will happen or not is uncertain.