Smooth Button Rollover

Question

I have been searching this topic for quite some time now, but
I still have not been able to figure it out. What I am trying to do
is make a button that when you roll over the button, it does a
smooth transition to a new color, then when you roll off of the
button it smoothly goes back to the original color. What really got
my attention was how surreal-media does alot of their links, where
its two colors usually...the top color fades to a new color on the
roll over, then fades back when you go off of it. Could someone
please explain this technique to me. I would be most grateful, and
will finally be able to rest a bit.

Answer 1

Thanks again. I'm getting closer! I used to have 2 rollover
repeats. The first was as you left the current page, the second
just after arriving at the new page. The on(rollOut) got rid of the
second one, but I still have a repeat immediately after release.
AmI putting the code in the right place? Here's the action script I
have for the button:
on (release) {
gotoAndPlay("HoAbout");
on(release){
_global.btnVar = true;
on(rollOut){
_global.btnVar = false;