function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function imgChange() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<imgChange.arguments.length; i+=2) {
			document[imgChange.arguments[i]].src = imgChange.arguments[i+1];
		}
	}
}

var preloadFlag = false;

function imgPreload() {
	if (document.images) {
		over_bt_1 = newImage('images/img_bt_gallery_o.jpg');
		over_bt_2 = newImage('images/img_bt_battle_o.jpg');
		preloadFlag = true;
	}
}