GIMP stuck at GTK 2 which prevents them to work properly on modern hardware. I hope they release 3rd version soon. They should have made Kickstarter campaigns like Krita did.
Funny that GTK was originally created for GIMP (GTK was acronym of "Gimp ToolKit"), and now they are 10 years behind the latest version of their own toolkit.
This shows how crazy the GTK rewrite was. Not even GIMP was willing to rewrite its code to use the latest version.
I'd definitely support this, but prefer Liberapay or other libre alternatives. It would suit free software projects better.
Github sponsers anyone?
There is a standalone MyPaint program that improves the HiDPI experience, but not having the rest of the features is wack.