If mouse over?

is there an way to use if structure to check if a mouse is over a button?
making a game in which i want to c if a user is withing an area with the mouse

[AS]
if(c1.onRollOver){
trace (wee);
}
[/AS]
dident work =/

(i need it to be in an if statement so i can keep checking if its over)

//VoS