[Zope] List All users with a given permission

[Stuart 'Zen' Bishop]

I suddenly find myself with a need to populate a list box with
all users with a given permission on a particular object.
Is there any nifty method hidden away to do this? Or would I be
reduced to crawling up the tree looking for userfolders and iterating
over the contents (could be a bit sluggish with 3000+ users...)

Perhaps I'll just require tying the username and verifying on form
submission :-)

 ___
   //     Zen (alias Stuart Bishop)     Work: zen@cs.rmit.edu.au
  // E N  Senior Systems Alchemist      Play: zen@shangri-la.dropbear.id.au
 //__     Computer Science, RMIT 	 WWW: http://www.cs.rmit.edu.au/~zen