//manages the drop down menus

var nTimeHide = 100;
var nTimerID = 0;
var nMenuItem = 0;

function showLayer( nId) {	
  clearTimer();
  if( nMenuItem) 
    nMenuItem.style.visibility = 'hidden';
  nMenuItem = document.getElementById( nId);
  nMenuItem.style.visibility = 'visible';
}


function hideLayer() {
  if( nMenuItem) 
    nMenuItem.style.visibility = 'hidden';
}

function setTimer() {
  nTimerID = window.setTimeout( hideLayer, nTimeHide);
}

function clearTimer() {
  if( nTimerID) {
    window.clearTimeout( nTimerID);
    nTimerID = null;
  }
}

document.onclick = hideLayer;