function toggleExtraOptions(on){
		$("tbody.extra"+on+"options").toggle();		
		if($("img."+on+"toggleimage").attr("src").indexOf('driehoekje_up.gif')!=-1){
			$("img."+on+"toggleimage").attr("src",'images/driehoekje_down.gif');
		}else{
			$("img."+on+"toggleimage").attr("src",'images/driehoekje_up.gif');
		}
	}