Advanced Lingo for Games by Gary Rosensweig is a GREAT source for these kinds of questions. This particular issue is dealt with head on in the "Space Invaders" chapter. He uses prepareFrame in a clever way if I remember right.
JB Tellez Lead Lingo Programmer Scientific Learning Corp. [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
