function intersect(rect, cropRect) {
		var x1, y1, x2, y2;

		x1 = max(rect.x, cropRect.x);
		y1 = max(rect.y, cropRect.y);
		x2 = min(rect.x + rect.w, cropRect.x + cropRect.w);
		y2 = min(rect.y + rect.h, cropRect.y + cropRect.h);

		if (x2 - x1 < 0 || y2 - y1 < 0) {
			return null;
		}

		return create(x1, y1, x2 - x1, y2 - y1);
	}
Returns the intersection of the specified rectangles.

@method intersect
@param {Rect} rect The first rectangle to compare.
@param {Rect} cropRect The second rectangle to compare.
@return {Rect} The intersection of the two rectangles or null if they don't intersect.