Positioning different size thumbnails

Hi everyone,
Havent been around for a while and not working with flash. So I have a problem I cannot solve on my own. I am using Scottys gallery and would like to use thumbnails with different widths. Right now they are loaded like this:

function makeButtons() {
	tnNr = 0;
	clearInterval(delay);
	for (var i = 0; i<tArray.length; i++) {
		var thb = thumbs.th_nav.thmb.duplicateMovieClip("thmb"+i, 1000+i);
		thb.id = i;
		thb._alpha=0;
		thb._x = i*120;
		thb.fader("fadeIn", 10, 100);
	}
	loadButtons();
}

Does anyone know how to space the thumbs based on their widht rather then a fixed width of 120px like used in my example?
Thanks for any help :wink: