Is it possible to create empty movieclip, mask, and move it?

programming flash
1

Hello!

I was wondering how you could move an empty movieclip that is set as a mask?

this.createEmptyMovieClip("mask", 1);
mask.setMask(square);
_root.mask._x +=10

I’ve tried using this code, but it does not work?

I’ll attach an swf of what I’m trying to accomplish, using this actionscript. Basically, I just want a picture to be revealed left-to-right without having to create a physical mask on the stage.

Is this possible?