Hi,
some time ago I have started writing an advanced metronome/rhythmbox plugin called Bobronome. At the time the project has been abandoned 'cause we have switched to the Android platform. The plugin consists of the rhythm box logic + multipurpose library. The library does some GUI (modeled like GTK), XML, threading and config objects. Memory efficiency and static allocation of the objects were in mind when designing the library. It is written for RockBox 3.4. Doxygen comments are mostly there and therefore doxy docs can be generated as well.
So, to the point: As the Bobronome is abandoned, there is nobody who actually works on it, but it is actually functional and because of the presence of the multipurpose library it is possible it might be of some use for somebody else.
I can't attach the zipped sources here, because the archive is 500kb
If anyone is interested I can send the code to you.
Cheers
Pavel