Help modifying button action to open an external link

I have this action for a button, what do I need to change to make it open an external link when button is clicked and the button stay selected/highlighted.

quote:

---

on(rollOver) {
num=4;
if(_root.link<>num){
gotoAndPlay("s1");
}}


on(rollOut, releaseOutside) {
num=4;
if(_root.link<>num){
gotoAndPlay("s2");
}}


on(release) {
num=4;
if(_root.link<>num and _root.animation==1) {
_root.animation=0;
_root.link_prev=_root.link;
_parent["item" + _root.link].gotoAndPlay("s2");
_root.link=num;
_root.play();

_root.scroller.scroller.gotoAndStop(3);
_root.DY = stage.height+4
_root.DX = stage.width+4

}
}

---

Thank you.