var objNavMenu = null;
var prevObjNavMenu = null;
var prevObjDropMenu = null;
var numDropMenu = 6;

var bgLinkColor = '#000';
var bgLinkHover = '#f00';
var bgLinkActive = '#900';
var linkColor = '#fff';
var linkHover = '#fff';
var linkActive = '#fff';
var isIE = null;

if(navigator.appName.indexOf('Microsoft Internet Explorer') != -1)
  isIE = 1;

function initDropMenu(){
  document.onclick = hideDropMenu;
  for(i = 1; i <= numDropMenu; i++){
    menuName = 'dropMenu' + i;
    navName = 'navMenu' + i;
    objDropMenu = document.getElementById(menuName);
    objNavMenu = document.getElementById(navName);
    objDropMenu.style.visibility = 'hidden';
    objNavMenu.onmouseover = showDropMenu;
    objNavMenu.onmouseout = menuOut;
    objNavMenu.onclick = showDropMenu;
  }
  objNavMenu = null;
}

function showDropMenu(e){
  menuName = 'drop' + this.id.substring(3, this.id.length);
  objDropMenu = document.getElementById(menuName);
  if(prevObjDropMenu == objDropMenu){
    hideDropMenu();
    return;
  }

  if(prevObjDropMenu)
    hideDropMenu();
  objNavMenu = document.getElementById(this.id);
  if(prevObjNavMenu != objNavMenu || prevObjDropMenu == null){
    objNavMenu.style.color = linkActive;
    objNavMenu.style.backgroundColor = bgLinkActive;
  }
  if(objDropMenu){
    objBar = document.getElementById('menuBar');
    xPos = objNavMenu.offsetParent.offsetLeft + objNavMenu.offsetLeft;
    //since offsetParent resolves to the body object on Firefox 3, use the menu bar
    yPos = objBar.offsetTop + objBar.offsetHeight;
    /*if(isIE){
      yPos -= 1;
      xPos -= 6;
    }*/
    // if there's something to display (may be just a link)
    if(objDropMenu.offsetHeight > 5){
      objDropMenu.style.left = xPos + 'px';
      objDropMenu.style.top = yPos + 'px';
      objDropMenu.style.visibility = 'visible';
    }
    prevObjDropMenu = objDropMenu;
    prevObjNavMenu = objNavMenu;
  }
}

function menuOut(e){
  document.onclick = hideDropMenu;
  objNavMenu = document.getElementById(this.id);
  objNavMenu.style.color = linkColor;
  objNavMenu.style.backgroundColor = bgLinkColor;
}

function hideDropMenu(){
  document.onclick = null;
  if(prevObjDropMenu){
    prevObjDropMenu.style.visibility = 'hidden';
    prevObjDropMenu = null;
    prevObjNavMenu.style.color = linkColor;
    prevObjNavMenu.style.backgroundColor = bgLinkColor;
  }
  objNavMenu = null;
}

window.onload = initDropMenu;