function rover(colore) {
colore = (!colore)?'':colore;
imgs = document.getElementsByTagName('img');
for (xx=0; xx<imgs.length; xx++) {
	
if (/top\.gif/.test(imgs[xx].src)) {
imgs[xx].onmouseover = function () {
this.src="img/top_hover"+colore+".gif";
}

imgs[xx].onmouseout = function () {
this.src="img/top.gif";
}
}

}

}