> Ever used a GTK app under Windows?

I have created and used them. They didn't look terrible on windows.

>What a browser asks from an OS is a rectangle (a graphics buffer) and the fonts to draw a webpage. Nothing else. Entire drawing functionality and the behavior is redefined from scratch. This is the advantage of Web..

I think that is exactly what Gtk does (and may be even Qt also) too..

I think it is just there there is not much funding going to those projects. Web on the other hand, being an ad-delivery platform, the sellers really want your browsers to work and look good...