First gothca is if you attach a movie clip/button and assign a handler to it such as “onPress”, it doesn’t know what _parent is. You have to use this._parent instead, as _parent will equal undefined.
Secondly, in optimizing my project using Buttons (as opposed to movie clips that just have button events assinged to them), I forgot that the Button class doesn’t natively support startDrag (2nd time I got bit), so instead of doing this.startDrag(false), you must do startDrag(this, false) instead. Same goes for stopDrag.