I think GTK+ shows how an open-source community can paint itself into a corner by becoming "too big to fail".<p>Gtk+ 1.0 was released in in 1998. Here's a list of vastly superior UI toolkits that were developed from scratch before Gtk+ 3.0 release:<p>* Microsoft's WPF (first release in 2006)
* Android's Java-based UI framework
* Palm's webOS UI framework
* Cocoa in Mac OS X (first release in 2001 - and before you nitpick, I know it was based on earlier tech from NeXT)
* iPhone UI (granted, based on Mac OS X UI but a lot of it was new)<p>The technology behind Gtk+ (C, even when written in a disciplined, object-oriented fashion) makes it painful to program against. It was fine when the alternative was Win32 but the above mentioned toolkits use higher-level languages (java, c#, javascript, objective-c) making them not only easier to program against but also easier to improve the toolkits themselves.<p>I don't follow Gnome development but my outsider perspective is that Gtk+ is a huge technical debt and there are no signs that the community is planning to ditch it for something that can go head-to-head with those other technologies (mono is the only initiative trying to move the state of the art of implementation technologies on unix but it doesn't have UI component (other than silverlight implementation, which is WPF-lite)).