// used to tell functions when images are loaded
var menuflag = 0;

// short names of each of the main menu buttons
var options = new Array('home','new','contact','conferences','research','awards','links','courses','who');
var overImgs = new Array();
var outImgs = new Array();

// path from this page to where the images are
var imgPath = "img/";

// function preloads images for main menu rollovers
function LoadMenu () {
  var n;
  
  if ( document.images ) {  
	for ( n = 0; n < options.length; n++ ) {
	  option_name = options[n];
	  overImgs[option_name] = new Image(); overImgs[option_name].src = imgPath + option_name + "_over.gif";
	  outImgs[option_name] = new Image(); outImgs[option_name].src = imgPath + option_name + "_off.gif";
	}
	menuflag = 1;
  }
}

// function to show default menu button image
function ShowOut ( id ) {
  if ( document.images ) {
	if ( menuflag ) {
		document.images[id].src = outImgs[id].src;
	}
  }
}

// function to display menu button mouseover image
function ShowOver ( id ) {
  if ( document.images ) {
	if ( menuflag ) {
		document.images[id].src = overImgs[id].src;
	}
  }
}

function ArrowOn ( id ) {
	if ( document.images ) {
		document.images[("a" + id)].src = imgPath + "orangeongrey_arrow.gif";
	}
}

function ArrowOff ( id ) {
	if ( document.images ) {
		document.images[("a" + id)].src = imgPath + "greyonwhite_arrow.gif";
	}
}