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) {
		mb_over = newImage("/math/mw/graphics/idx_btn_mb_o.gif");
		vc_over = newImage("/math/mw/graphics/idx_btn_vc_o.gif");
		tt_over = newImage("/math/mw/graphics/idx_btn_tt_o.gif");
		lp_over = newImage("/math/mw/graphics/idx_btn_lp_o.gif");
		ps_over = newImage("/math/mw/graphics/idx_btn_ps_o.gif");
		mah_over = newImage("/math/mw/graphics/idx_btn_mah_o.gif");
		mi_over = newImage("/math/mw/graphics/idx_btn_mi_o.gif");
		tm_over = newImage("/math/mw/graphics/idx_btn_tm_o.gif");
		prb_over = newImage("/math/mw/graphics/idx_btn_prb_o.gif");		
		wrc_over = newImage("/math/mw/graphics/idx_btn_wrc_o.gif");
		preloadFlag = true;
	}
}