thanks for this great work. I use your App on an Android device (Kindle Fire HD) and it works very well. I use it to acompany while playing a solo instrument.
One feature I am missing is to enable a metronome.
I am a also a software developer and so I added this functionality for the android sources. If you like, you can take this piece of code and use it for the other branches too.
I have added a checkbox "Play Metronome Ticks" to the settings page. If it is enabled, an invisible track is generated which contains percussion events giving the beat.
The code is not optimal. The metronome events are always generated, even if the checkbox is unchecked. So, if you are interested in adding this feature, I would like to work over the code.
Attached is a patch generated from eclipse.