UML modelling package

Can someone recommend a UML modelling package for QNX please? I’m not bothered about generating code (although it’d be nice) I just want to knock something up and I’m looking for some steer.
I’ve had a quick look at the mdt-uml2tools Eclipse plugin but I don’t seem to be able to do compositions/aggregations, I guess because it’s java related.

Any thoughts or recommendations greatly appreciated.