Admittedly, it could be done (replace the HildonButton with a HildonPickerButton and add a HildonTouchSelector with Dual, 3G and GSM in it) but, again, it would just make it time consuming. I decided to make it 2G/3G switch only because, TBH, I wonder what you would want with such an applet if you allow the phone to switch between the modes for you. But, anyway, the source code will soon be in extras-devel (it's been uploaded and built) so feel free to modify as you wish.