GTK+ was my first foray into GUI programming when I was a kid, and I still think it's pretty slick. I really liked the concept of boxes and nesting stuff, and how it would figure out how to lay it out. And that it could all be done in code and be understandable! Not some wonky OLE2 / Swing "Form Designer" that I was doomed to never understand.
Actually Swing works pretty much the same way, which is why I liked it. What I couldn't stand was stuff like Qt, which wants to generate / pre-process a lot of code.
I've decided my rule is, I want to either do everything in code (like GTK) or nothing in code (like Cocoa), but none of this "here's a utility that generates code for you" like Windows Forms.
I think they really cleaned this up in the Qt3 -> Qt4 transition - your Qt Designer forms are still turned into code, but not in a generated file that you're supposed to edit. Instead it's a standalone class that you inherit in your own class.
So uic and moc are still there, but they may as well be generating object code - you never have to read the C++ that they spit out.
To me the Qt and Cocoa approaches look the same. Qt is built on top of C++ pretty much the same way Objective-C is built on top of C: there is some syntactic sugar to allow dynamic binding and you do not ever have to look at the intermediate results if you do not want to. You can hack into the details of the implementation if you prefer, and you can do it in both frameworks.
