Can I add children through functions?

Question

I'm working on my first basic Flash game, essentially a platformer with obstacles determined by a random number generator. The idea is that when the player character reaches a certain coordinate, the next obstacle will be created. However, I'm having some problems creating new children by functions. For practice, I was just trying to add a square through a mouse event.
import flash.events.MouseEvent;
import flash.display.MovieClip;
var square:Square = new Square();
square.x = 100;
square.y = 100;
this.addEventListener(MouseEvent.CLICK, _mouse);
function _mouse(e:MouseEvent):void {
          this.addChild(square);
          trace("Trace");
The symbol is called "square" and is exported as a class called "Square". When I click, I want it to create the square while tracing a message, but when I click, absolutely nothing happens, not even the tracing. When I move the this.addChild(square) outside of the function, the child is added where it should, at x = 100 and y = 100 and the mouse event works and the message is traced. When I place the addChild inside the function, neither works, neither the addChild or the trace.
I'm flying completely blind here and have no idea what I'm doing, or what to search to look for help, so I figured this would be the best place to look.

Answer 1

Don't attach the event listener to "this". Use a defined object, in this case "stage" will work. Inside the function, which is connected to the stage through the event listener, the line "this.addChild(square);" the "this" refers to the stage and so it will add the child object "square" to the stage. But you don't really need to use the reference to either stage or this when adding that child.
Here's a lengthy discussion of "this": http://stackoverflow.com/questions/5321199/this-and-stage-in-as3