Eh, I don't know. I think that existence of crossword/todolist GTK apps is not nearly as much of a win as GIMP, Inkscape, Krita, KiCAD, FreeCAD and Scribd becoming actually competitive would have. It's indicative that biggest OSS app success, Blender, is not using OSS graphics library but rolls it's own UI. Rawtherapee, very highly regarded RAW file editor uses Qt. There's no decent looking mp3 player on Linux for heaven's sake! Every one that exists looks like shit or has zero functionality.