function isLastSlide() {

		if( currentSlide ) {
			// Does this slide have a next sibling?
			if( currentSlide.nextElementSibling ) return false;

			// If it's vertical, does its parent have a next sibling?
			if( isVerticalSlide( currentSlide ) && currentSlide.parentNode.nextElementSibling ) return false;

			return true;
		}

		return false;

	}
Returns true if we're currently on the last slide in
the presentation. If the last slide is a stack, we only
consider this the last slide if it's at the end of the
stack.