I know that this topic is very old, and fiffi probably isn’t even interessted in writing a QNX shelf plugin anymore.
However I think this is a very interesting topic for everone using QNX as a Desktop, so here is what I found today:
there is a Plugin showing the free diskspace for harddisks, it is availabe as .so and (!!) source, so everyone interested in in writing plugins can have a look at the code…