When a user stops or pauses a render in encoder I would like to know, so I can handle it in the panel.
Currently it returns type progress and progress at 1.0.
PPro will send you an error if they cancel; I'm not sure what you'll get as progress messages, when the render is paused; maybe check the interval between progress messages?
I have an onEncoderJobError bound which doesn't fire when they cancel, the progress I get back is 1.0 which is the same when the render completes.
What version? Not sure when we fixed it; might be in a near-future version.