[viraptor]

It doesn't. The point is that for tiny apps it doesn't matter - you can replicate that interface in 3 toolkits very easily.

Same applies to applications that want to display 3 edit boxes, an image and 2 buttons. Just do it in the native framework 3 times. It's not that much work.

[schneegans]

Well, the WYSIWYG menu editor of Kando is one if the most complex nonstandard UI elements I have written so far. That's an aweful lot more than a few buttons.

Also, there is usually no ready-made pie menu widget in native frameworks. So you will have to draw the menu yourself with low-level shapes like boxes, circles, and text. If you want these to be themeable, if you want to have a powerful animation engine, and if you want that your scene is efficiently drawn even at high resolution with several hundreds of said shapes moving around your screen, things get quickly much more complex than you may think...

And soon you will realize that CSS and modern browser engines are exactly optimized for this.