Almost all of Qt apps in the world extend the basic framework to include their own widget sets and APIs. Even on desktop, some of the more serious commercial application use Qt as the core commonality but not to write a single app that magically works across platforms: they want the platform differences but also relatively cheap porting and a common set of tools.

This maybe is less than perfect, but I believe that that's reality and it's going to remain reality for a good reason.

When you try to limit mobile application developers to what a cross-platform framework can do without some platform-specific extensions, you end up with something more like J2ME or very basic HTML. Generalizing UI needs in a cross-platform way takes time, more time than Nokia and other companies have if they want to innovate in a way that reacts to market needs.

To be more precise, we COULD have a 100% common API that would allow for the awesome new touch UIs and would work great on Maemo and Symbian devices, but it would probably be ready a couple of years from now - when we already want the newer thing.

What is probably more practical is letting Maemo/Symbian innovate on their time frames, and later take the common parts into the core framework. Qt has done this with KDE for years.

Qt is an excellent cross platform TOOLKIT, and if seen as such, it makes perfect sense (at least to me). It's the core for building great DUI apps for Maemo, great Orbit apps for Symbian, and later QML apps (some of which will be fully portable, some will include DUI/Orbit specific components).

There's always a difference between what a purely cross-platform app can do (whether it's QWidget / QGraphicsView / QML / WRT) and what an app with a specific platform in mind can do. Show me a solution that solves that problem - Android tried but I don't think they've proven success (see posts about subtle fragmentation between Android phones - J2ME deja-vu).

With Qt you can port the pure cross-platform apps for free, and the platform-specific apps for cheap (as QGraphicsView is still the core for both Dui and Orbit). It is my belief that that's the role Qt should have!