So one of the first things you might wonder is “what’s my width?” Probably the first thing you’ll do is just test this.width (ie, the width of the current sprite). However, it’s zero. Then you might think to try stage.width, but it’s also zero. The correct answer is stage.stageWidth.
As for the others, they describe the current width of what has been drawn, not the canvas size. In other words, they will stay zero until you start drawing, and then they’ll describe the total width (in pixels, I think — or maybe in the parent coordinate system, which by default is pixels. I’m still working that out) of what has been drawn so far.
