This is such a troll statement that I’m not even sure how to respond to it in a way that doesn’t devolve in me banning your account from this forum.
The fact that you’re not aware of solutions to your issues, and you don’t have volunteers at your beck and call, does not imply that GTK is unused, or that your problems have never been considered or encountered before. Quite frankly, it’s insulting to the work that people have done over two decades.
I strongly encourage you to move away from GTK, and just use another toolkit.