Hm, it might have to do with the way CSS works.. When I'm developing gtk+ Applications, I always do the UI in glade. It works wonderfully, even if I still have to do some stuff in code (UI elements that are added in response to the user doing something). And even for that there seems to be an alternative, namely GtkBuilder templates – haven't tried that yet and Glade doesn't seem to be able to create them, but might be able to edit them once you have manually written the first few lines of XML.
Good point. I've never actually worked with gtk+, but I have worked with windows forms development for desktop apps. I thought it was a really good approach for building a windows desktop applications, but I create all web-based UIs in a code editor.
I suppose if there was only one browser to target, then we might actually see more use of a GUI editor. Kind of how FrontPage was for IE a long time ago.
