// The selected item.
var nav_selected = new Array();

// Sets the subnav display style if the subnav tab exists.
function nav_subnav_set_display( tab, display) {
  var obj = $('subnav_' + tab);
  if( obj != null && typeof(obj) != 'undefined') {
    obj.style.display = display;
  }
}

// Hide all subnav items.
function nav_hide_all(location_subnav_id) {
  var children = $(location_subnav_id).childNodes;
  for( var i = 0; i < children.length; i++) {
    if( children[i].nodeType == 1 && children[i].id != null && children[i].id.indexOf('subnav_') == 0) {
	  // If it's the first time we hide all, save the subnav that is currently selected.
	  if( nav_selected[location_subnav_id] == null && children[i].style.display == '') {
		  nav_selected[location_subnav_id] = children[i];
	  }
	  // Hide each subnav.
      children[i].style.display='none';
    }
  }
}

// Main navigation onmouseover.
function nav_main_over(tab, location_subnav_id, is_empty) {
  nav_hide_all( location_subnav_id);
  nav_subnav_set_display( tab, 'none');
  $(location_subnav_id).className='';
  if( !is_empty) {
    nav_subnav_set_display( tab, '');
    $(location_subnav_id).className='on';
  }
}

// Main navigation onmouseout.
function nav_main_out(tab, location_subnav_id) {
  nav_subnav_set_display( tab, 'none');
  $(location_subnav_id).className='';
  if( nav_selected[ location_subnav_id] != null) {
    nav_selected[ location_subnav_id].style.display='';
    $(location_subnav_id).className='on';
  }
}

// Subnav onmouseover.
function nav_subnav_over(tab, location_subnav_id) {
  nav_subnav_set_display( tab, '');
  $('nav_' + tab).className='nav_' + tab + ' on';
  $(location_subnav_id).className = 'on';
  if( nav_selected[ location_subnav_id] != null) {
    nav_selected[ location_subnav_id].style.display='none';
  }
}

// Subnav onmouseout.
function nav_subnav_out(tab, location_subnav_id) {
  nav_subnav_set_display( tab, 'none');
  $('nav_' + tab).className='nav_' + tab;
  $(location_subnav_id).className= '';
  if( nav_selected[ location_subnav_id] != null) {
    nav_selected[ location_subnav_id].style.display='';
    $(location_subnav_id).className='on';
  }
}