First, you should make an ellipse shape MovieClip like Balloon. and refer a following skeleton-code. Clicking on the stage, this code toggles the balloon inflation to deflation versa.
and here is source code link: Ballon_Sample
import flash.events.MouseEvent;
import flash.events.Event;
var isToggle:Boolean;
var ballonState:String = "default";
stage.addEventListener(MouseEvent.CLICK, onClick);
stage.addEventListener(Event.ENTER_FRAME, onEnter);
function onClick(e:MouseEvent):void
{
if(!isToggle)
{
ballonState = "inflate";
}
else
{
ballonState = "defalte";
}
isToggle = !isToggle;
}
function onEnter(e:Event):void
{
if(ballonState == "inflate")
{
//mc_ballon is Ellipse Shape MovieClip like Ballon Shape.
mc_ballon.scaleX += 0.01;
mc_ballon.scaleY += 0.01;
}
else if(ballonState == "defalte")
{
mc_ballon.scaleX -= 0.01;
mc_ballon.scaleY -= 0.01;
}
}