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

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

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
	    twbutton_over = newImage("../images/twbutton_over.gif");
	    cwbutton_over = newImage("../images/cwbutton_over.gif");
	    gdbutton_over = newImage("../images/gdbutton_over.gif");
	    thbutton_over = newImage("../images/thbutton_over.gif");
	    pebutton_over = newImage("../images/pebutton_over.gif");
	    cobutton_over = newImage("../images/cobutton_over.gif");
	    hobutton_over = newImage("../images/hobutton_over.gif");
		
	    preloadFlag = true;
	}
}