// H.P. de Vries


// this array contains opened divs to be collapsed
var popmenu_opened = new Array();

function div_hide(div) {
	document.getElementById(div).style.visibility = "hidden";
}

function div_show(div) {
	document.getElementById(div).style.visibility = "visible";
}

function div_toggle(div) {
	var menulevel = div.substring(10,11);
	var menunumber = div.substring(12);

	if (document.getElementById(div).style.visibility == "visible") { // this div is hidden, so hide it and all undelying menus
		document.getElementById(div).style.visibility = "hidden"; // hide element -> collapse menu up to this level
		document.getElementById("poplink_"+menulevel+"_"+menunumber).className = "";
		if (img = document.getElementById("poplink_img_"+menulevel+"_"+menunumber)) img.style.visibility = "hidden";
		popmenu_opened[menulevel] = "";	
		while ( i = popmenu_opened.pop() ) { // process all open menus until null encountered (= collapsed level)
			div_hide(i); //
			document.getElementById("poplink_"+i.substring(10,11)+"_"+i.substring(12)).className = ""; // remove background
			if (img = document.getElementById("poplink_img_"+i.substring(10,11)+"_"+i.substring(12))) img.style.visibility = "hidden"; // hide arrow
		}
	}
	else { // open new div. check if above this level already open.
		if (popmenu_opened[menulevel]) { // there are levels above this level open
			var i = menulevel;
			while ( j = popmenu_opened[i] ) {
				div_hide(j);
				document.getElementById("poplink_"+j.substring(10,11)+"_"+j.substring(12)).className = "";
				if (img = document.getElementById("poplink_img_"+j.substring(10,11)+"_"+j.substring(12))) img.style.visibility = "hidden"; // hide arrow
				i++;
			}
		}
		document.getElementById(div).style.visibility = "visible"; // open element -> open menu popmenu_d_a_b (a = level, b = #)
		document.getElementById("poplink_"+menulevel+"_"+menunumber).className = "activemenu";	// colour background
		if (img = document.getElementById("poplink_img_"+menulevel+"_"+menunumber)) img.style.visibility = "visible";	// show arrow
		popmenu_opened[menulevel] = div;
	}
}	

function cijfers(evt) 
{
  var charCode = (evt.which) ? evt.which : evt.keyCode; 
  if ((charCode >= 48 && charCode <=57) || charCode == 8) 
  { 
   return true; 
  } 
return false;
}