function changeDisplay(div_id,if_,then_)
{
 var elem=document.getElementById(div_id);

 if (elem)
 { 

 if (elem.style.display==if_) {elem.style.display=then_;}
 }
} 
function open_sub(SM_SHORT)
{

	if (akt_sub!=SM_SHORT) {
  
	   
		 changeDisplay(akt_sub,'block','none');
		 changeDisplay(SM_SHORT,'none','block');
/*		 changePfeil(document.getElementById(akt_sub),'out');*/
		 akt_sub=SM_SHORT;			   
	}

}
function changePfeil(obj, todo)
{
  if (obj.id!=('FOLDER_'+akt_sub))
	{
    vis="visible";
 	  if (todo=='out') {vis="hidden";} 
  	obj.getElementsByTagName("img")[0].style.visibility=vis;
	  
	}	
		


}