How to stop player from walking on walls - actionscript-3

Question

I'm building a test avatar chat... thingy in ActionScript3, but I've come across a problem, whenever I click the chatbar to say something, my avatar (which is currently a penguin) walks to it -- how can I prevent this from happening? In other words, how do I build a wall and keep the penguins out?
This is the code I'm using to make my penguin move.
stage.addEventListener(MouseEvent.CLICK, myClickReaction);
// speeds ALONG NYPOTENUSE
var v:Number = 7;
// vector of movement
var dir:int = 100;
// mouse click point
var clickPoint:Point = new Point();
// angle doesn't change metween clicks - so it can be global
var angle:Number;
function myClickReaction (e:MouseEvent):void {
clickPoint = new Point(mouseX, mouseY);
angle = Math.atan2(clickPoint.y - penguin.y, clickPoint.x - penguin.x);
dir = angle >= 0 ? -1 : 1;
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
function onEnterFrame(e:Event):void {
var projectedX:Number = penguin.x + v * Math.cos(angle);
var projectedY:Number = penguin.y + v * Math.sin(angle);
var diff:Number = clickPoint.y - projectedY;
if (diff / Math.abs(diff) == dir) {
penguin.x = clickPoint.x;
penguin.y = clickPoint.y;
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
}
else {
penguin.x = projectedX;
penguin.y = projectedY;
}
}