There are two ways (that I can think of) to do this. One would be to have a
second identical action button (except with the different color) set to
have an entrance effect that is triggered by the first action button. This
will work in PPT 2002 and later.
The other way is to use macros to change the color of the action button.
Let me know if you want some sample macros.
--David
--
David M. Marcovitz
Microsoft PowerPoint MVP
Director of Graduate Programs in Educational Technology
Loyola College in Maryland
Author of _Powerful PowerPoint for Educators_
http://www.loyola.edu/education/PowerfulPowerPoint/