I've used a Fetch Chop to see the Paint sop parameters.
I then deleted all the unwanted params leaving just the events ones.
In the Paint Sop - Stroke - Event there is a little menue that has a Click value.

Unfortunately, while I can see the changes in Chop for all other events, nothing seems to happen on click.
Any ideas? or is this a bug?

Thanks

The Stroke Event is a numerical indicator of which event is occurring, so if you paint on the surface and watch in the Stroke folder of the Paint sop you'll see the Event changing.
You should see the Event parameter in the Fetch chop changing between a range of 0 to 4.

hi, i've there are 4 events being seen in Chops but there are 5 in the Events list. No change is registered at all on the when I click the mouse.

I didn't say there were 4 events, I said the range was from 0 to 4, which represents 5 events.
Do you have the display flag on the Fetch chop? Do you have the correct Event parameter name declared?