How about keeping a seperate boolean variable?
var clicked:Boolean = false;
var Modifier:int = 1;
stage.addEventListener(MouseEvent.CLICK, Happening);
public function Happening(e:MouseEvent):void{
if(clicked){
//return to default
Modifier = 1;
clicked = false;
}else{
Modifier = 4;
clicked = true;
}
}
or even simpler
if(Modifier==4){
Modifier=1;
}else{
Modifier=4;
}
or in one line
Modifier = (Modifier==4) ? 1 : 4;