function openWinCentered(mypage, myname, w, h, scroll, resize) {
	var winl = (screen.width - w) / 2;
	var wint = (screen.height - h) / 2;
	winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',scrollbars='+scroll+',resizable='+resize;
	win = window.open(mypage, myname, winprops)
}

function openTricks() {
	openWinCentered('images/tricks_600x600.gif', 'tricks', 620, 620, 0, 0);
}