Basic Action Script 3 question

Question

I've been watching a tutorial on making a thumbnail photo gallery with Flash. Unfortunately the only tutorial I could find that explained everything step by step was for Flash MX and I'm using Flash CS4. It seems that the scripting code is different. I've never written Flash script before. I am trying at this point to give a rollover effect to a thumbnail image, so when the mouse goes over the thumbnail the thumbnail will get brighter. The code given in the tutorial didn't work, but by looking at the debugger messages it seems like the script should be something like:
thumb1.addEventListener(MouseEvent.MOUSE_OVER,mouseOverHandler);
function mouseOverHandler(event:MouseEvent):void {
thumb1.DisplayObject.alpha=100;
I converted the thumbnail to a button symbol and then created an instance of the button called thumb1. The code is applied to a keyframe.
Am I close with the code? How should it look?
Thanks - Eric

Answer 1

In Flash CS4 you can publish to either AS3 or AS2. The AS2 in CS4 is pretty much the same as it was in Flash MX (also known as Flash 6) — although there were some updates to AS2 since 2001!
So if you want to use the tutorial as is, you would go to the Flash publish settings and change it to AS2.
If you want to learn AS3 (and I would recommend that you do and forget AS2) you should be able to find tutorials for this. The code you gave isn't quite right. I don't know what that DisplayObject is doing in there. That is the name of a Flash Class, so you shouldn't give instance that as a name. I'm thinking your code should be something more like this:
thumb1.addEventListener(MouseEvent.MOUSE_OVER,mouseOverHandler);
thumb2.addEventListener(MouseEvent.MOUSE_OVER,mouseOverHandler);
function mouseOverHandler(event:MouseEvent):void {
     event.currentTarget.alpha=100;
There are also a lot of other ways to do this, but this is one of the simplest to understand.