I'm wondering how the UI of e.g. Opera Mini, Adobe Reader or the new Twitter application is made on Android. Both of them use very different looking controls than what the OS provide in default. Are they using the platform's theming method to create these or a canvas and draw everything byself on top of that or maybe completly "from scratch" written widgets?
I'm searching on the web for tutorials to make such kind of programs, but i don't found anything useful. Google hasn't released the source code for the Twitter application yet; i'm waiting for it since the Google IO.