Part of the reason they are so often used is that they are easily designed and easily performant. If something is a simple circle, you can load a graphic (or design an effect/shader) and simply rotate it.

If it's more involved (like the suggestion a few posts up), you generally either have to do horrible crap like qt-components did and load each frame of the image in sequence based on a timer, or load an animated image, or something. Neither are really appealing options.

*edit* especially considering Qt 5.2 has the capability to run animations that are simplistic enough entirely on the render thread: http://doc-snapshot.qt-project.org/q...-animator.html

I wouldn't imagine that using colorAnimation on 4 standard qml Rectangles would be less performant than loading an image and rotating it.

I didn't say it wasn't, although creating four rectangles (and four animations) plus bindings and property settings between them is a lot more work, but then we're talking on a rather minute-level, and for a component like a busy indicator, that sort of consideration doesn't matter. On the other hand, if you're working on something like Label, where a bad property binding can be the difference between 0.x ms and 2ms to create a single Label -- that sort of thing does matter when you're creating tens or hundreds of them in a typical application, or while panning.

I'm not drawing direct comparisons here, I'm just noting that performance is (or should always be) a concern when designing something. Otherwise you end up with compromises somewhere further down the line (precreating, caching, prestarting applications, or just being slow...)

I really like this mockup. I hate flat GUI.

I wish These Kinda UI Come to Nokia N900.

It seems different people perceive flat in different ways. This mockup is flat in my eyes (or at least, almost flat).

Nevertheless I'm glad you like it.

P.S. non-flat by my standards:

The best thing about this UI is that it is all black as default. Just like N900. I hate all these extremely bright UI as in iOS and Android. Even at lowest brightness. Hurts my eyes.

i have an idea about multi tasking
to close an app user should just tap and hold on a minimized app
and to close all apps, after holding a finder for a longer time, a dialogue would appear asking whether to close all the apps

Let's refine that, because some apps might actually benefit from that in such an app view:
- tap and hold on the top left or right corner of the app in the multi-tasking view and it will close
- tap and hold anywhere else on the app window and get options for other stuff (refresh view, look for updates, answer/reject, play/pause/next/previous, capture app screenshot, send/share, etc.)
- tap and hold on any spaces in between the app windows and get the prompt to refresh all, close all, delete apps, and backup

Nice idea. Appreciate an ability to think through it and see what else is there.

no, I haven't.