// JavaScript Document


function menu_roll(obj) {
	var base;
	var extension;
	var filename;
	var lastSlash = obj.src.lastIndexOf("/");
	var extStart = obj.src.lastIndexOf(".");
	
	base = obj.src.substring(0, lastSlash + 1);
	extension = obj.src.substring(extStart);
	filename = obj.src.substring(lastSlash + 1, extStart);
	
	//alert("base: " + base + "\n" + "ext: " + extension + "\n" + "filename: " + filename + "\n");
	
	if(filename.indexOf('_on') > 0  ) {
		var newfilename = filename.substring(0, filename.lastIndexOf('_on'));
		obj.src = base + newfilename + extension;
	} else {
		obj.src = base + filename + "_on" + extension
	}
	
	
}