var SubMenuActive = '';
dom = (document.getElementById)? true : false;
nn4 = (document.layers)? true : false;
ie4 = (!dom && document.all)? true : false;

function displayElem(id) {
  if (dom) document.getElementById(id).style.display = "block";
    else if (ie4) document.all[id].style.display = "block";
      else if (nn4) document.layers[id].display = "block";
  
}

function undisplayElem(id) {
  if (dom) document.getElementById(id).style.display= "none";
    else if (ie4) document.all[id].style.display= "none";
      else if (nn4) document.layers[id].display= "none";
}

function showSubMenu(divn, img) {
	if (SubMenuActive != ''){
		document.images[img].src="leftmenu_kn1.gif";
		undisplayElem(SubMenuActive);
	}
	if (SubMenuActive != divn){
		document.images[img].src="leftmenu_kn1_a.gif";
		displayElem(divn);
		SubMenuActive = divn;
	}else{
		document.images[img].src="leftmenu_kn1.gif";
		undisplayElem(SubMenuActive);
		SubMenuActive = '';
	}
}