plugin sliders no-worky

I’m using ardour2 v 2.8.12
on an aluminum 12" Powerbook 1.5mhz G4.
I just realized that on this model I cannot select double-finger tap right-clicking as was suggested on the “before downloading” page.
I think my real problem is unrelated though and is as follows:
When I open an AU plugin window so as to edit the parameters I am unable to move the sliders?
Is there something tricky I’m missing or is it broken?

Thanks in advance!

forgot to say:
OSX 10.4.11

Hmm sounds like a bug to me, make sure you file it in Mantis, but if you have time to get on IRC via Help>Chat during the daytime EST next week it would help to go through some things with you there in faster time than forums allow.