WARNING: Actions on button

Question

Hi
I do not understand why I am getting this warning below
WARNING: Actions on button or MovieClip instances are not supported in ActionScript 3.0.
All scripts on object instances will be ignored.
Can someone help?
mimi

Answer 1

You can still use pretty much any objects that you have ever used before, though that's not saying they haven't changed in some way. In AS3 to manage things like buttons and other interactions the primary code approach involves creating event listeners and event handler functions.  Here is a description of how you would approach coding a button, though the same could apply to a movieclip....
Let's say you create a button symbol.  Since it is a button, it is already a self animating object that will react to mouse interactions, but only visually at this stage.  The first thing you need to do to make it useful code-wise is to assign it a unique instance name.  So you drag a copy of it out to the stage from the library, and while it's still selected, you enter that unique instance name for it in the Properties panel... let's say you name it "btn1"
In AS3, to make a button work with code, you need to add an event listener and event handler function for it.  You might need to add a few (for different events, like rollover, rollout, clicking it, but for now we'll just say you want to be able to click it to get a web page to open.  In the timeline that holds that button, in a separate actions layer that you create, in a frame numbered the same as where that button exists, you would add the event listener:
btn1.addEventListener(MouseEvent.CLICK, btn1Click);
The name of the unique function for processing the clicking of that button is specified at the end of the event listener assignment, so now you just have to write that function out:
function btn1Click(evt:MouseEvent):void {
   gotoAndPlay("site_section");
Here's some of what's involved there:
evt:MouseEvent - the event listeners throws an argument automatically which the function must be set up to receive.  In this case I have given that argument a variable name of evt, though I could have chosen anything.
:void - this defines the class of the value that the function will return.  In this case, the function does not return anything, so "void" is used.  If it did return a value, you would see a line containing "return xyz"; in the function (where xyz is not literal, it simply represents the variable or value being returned) and the :void would be rplaced with some other class such as :String, :int, Date, etc....
In AS3, in strict mode, it is necessary to identify the types/classes of the variables being created, which is why you see :String, :MouseEvent, etc... showing up everywhere.
Now, to create another button with a unique function for it, you could just drag another copy of it from the library, give it a unique name, say btn2, copy/paste the code from btn1 and replace "btn1" with "btn2" in that copied code.