// preload navigation images

function preload_aboutsubnav() {
if(document.images) {
  var ImgArray = new Array();
  for (var i = 0; i < 10; i++) {
    ImgArray[i] = new Image();
  }    
	ImgArray[0].src = "images/subnav_about.gif";
	ImgArray[1].src = "images/subnav_about_on.gif";
	ImgArray[2].src = "images/subnav_program.gif";
	ImgArray[3].src = "images/subnav_program_on.gif";
	ImgArray[4].src = "images/subnav_book.gif";
	ImgArray[5].src = "images/subnav_book_on.gif";
	ImgArray[6].src = "images/subnav_video.gif";
	ImgArray[7].src = "images/subnav_video_on.gif";
	ImgArray[8].src = "images/subnav_classroom.gif";
	ImgArray[9].src = "images/subnav_classroom_on.gif";
  }
}


function on(feature) {
	if(document.images) {
		var foo = eval('document.' + feature);
		foo.src = 'images/subnav_' + feature + '_on.gif';
	}
}


function off(feature) {
	if(document.images) {
		var foo = eval('document.' + feature);
		foo.src = 'images/subnav_' + feature + '.gif';
	}
}