var preloadFlag;
function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}
function preloadImages() {
		boat = newImage('title/images/boat.png');
		snorkel = newImage('title/images/snorkeling.png');
		fun = newImage('title/images/fundiving.png');
		intro = newImage('title/images/intro.png');
		learn = newImage('title/images/learn.png');
		emph = newImage('title/transp0.gif');
		preloadFlag = true;
}
function changeImages(imageName,pngName) {
	var img;
	img=document.images[imageName];
	img.src=pngName;
}
function on_image(arg){
	document.getElementById(arg).style.visibility="visible";
}
function off_image(arg){
	document.getElementById(arg).style.visibility="hidden";
}
function on_switch(arg){
	document.getElementById(arg).style.backgroundImage="url(title/switch_on.jpg)";
}
function off_switch(arg){
	document.getElementById(arg).style.backgroundImage="url(title/switch_off.jpg)";
}
function on_emph(arg){
	document.getElementById(arg).style.backgroundImage="url(title/transp0.gif)";
}
function off_emph(arg){
	document.getElementById(arg).style.backgroundImage="url(title/transp.gif)";
}