function preloadImages()   {
	img_on_specialevents=new Image();
	img_on_specialevents.src="images/nav_specialpic_on.gif";
	img_on_specialevents=new Image();
	img_on_specialevents.src="images/nav_exhibitpic_on.gif";
	img_on_specialevents=new Image();
	img_on_specialevents.src="images/nav_setdesignpic_on.gif";
}