function $(id){
		return document.getElementById(id);
	}
	window.onload = function(){
        if($('projecten_lijst')){
		    if($('projecten_lijst').clientHeight > 400||$('projecten_lijst').offsetHeight > 400){
			    $('submenu_down').style.visibility = $('submenu_up').style.visibility = "visible";
    		}
        }
        if($('content_text')){
          if($('inner_content').clientHeight > $('scoll_div').clientHeight||$('inner_content').offsetHeight >$('scoll_div').offsetHeight){
  		    	$('scoll_div').style.visibility = "visible";
  	    	}
        }
	}
	var  scroll_timeout;
	function stopscroll(){
        clearInterval(scroll_timeout);
	}
	function scrollup(div_id){
		clearInterval(scroll_timeout);
		scroll_timeout =setInterval('scroll(true)',10);
	}

	function scrolldown(div_id){
		clearInterval(scroll_timeout);
		 scroll_timeout =setInterval('scroll()',10);
	}

	function scroll(up){
		if(up){
			$('content_text').scrollTop-=3;
		}else{
			$('content_text').scrollTop+=3;
		}
	}