Thx for your reply, chuck..
But i want to keep it easy.. so what i am doing now... is:
A. for non ACP pages..( public pages) i check if ppg_options is there..
if($ppg_options && is_array($ppg_options))
and for acp i just add an option that says: If you have vbgallery installed then show special gallery options to users.... YES / NO
I was going to hide that option in acp if vbgallery is not installed...
but now, well, its only a dummy option if vbgallery is not installed...
(BTw: its going to be a facebook style tool bar.. on all pages.. with a modal window that handles lots of features with ajax) .. I'll set up a demo as soon as I got something to show...)