function doTooltip(e, msg) {
  if ( typeof Tooltip == "undefined" || !Tooltip.ready ) return;
  Tooltip.show(e, msg);
}

function hideTip() {
  if ( typeof Tooltip == "undefined" || !Tooltip.ready ) return;
  Tooltip.hide();
}

function doPhotoHover(e, photoname, imgname, creditname) {
	var tip = '<div class=tip><span class=artist>'+photoname+'</span><br/><img src=img/'+imgname+' width=150 height=150 />';
	if (creditname != null && creditname != "undefined" && creditname != "") {
		tip += '<br/><div class=photocredit>photo by '+creditname+'</div></div>';
	}
	doTooltip(e, tip);
}