function jam_popup(url,opts){
	/* ACHTUNG IE ignoriert das erste Argument aus opts (daher als erstes menubar=0 übergeben)!! */
	var helpopts = new Array();
	helpopts = opts.split(",");
	for	(var i=0; i<helpopts.length; i++) {
		if (helpopts [i]) {
			eval(helpopts [i]);
		}
	}


	if (opts.length == 0) {
		opts = "menubar=no";
	}

	/* Standardgröße setzen, wenn nicht übergeben */
	if (opts.indexOf("width") == 0) {
		opts += ",width=500px";
	}
	if (opts.indexOf("height") == 0) {
		opts += ",height=400px";
	}

	/* Positionieren */
/*	opts += ",left=100px";
	opts += ",top=100px";*/
	opts += ",left=" + Math.round((screen.availWidth  - Number(width ))/2) + "px";
	opts += ",top="  + Math.round((screen.availHeight - Number(height))/2) + "px";

	jampopwin = open(url,'jampopwin',opts);
	jampopwin.focus();
}