function limpiarSrc(str){
	return str.replace(/-pressed.jpg/, ".jpg");
}

function rollOver(){
	src = limpiarSrc(this.src);
	if(src.indexOf("-hover") < 0 && this.src.indexOf("pressed") < 0){
		this.src = this.src.replace(/.jpg/, "-hover.jpg");
	}
}
function rollOut(){
	src = limpiarSrc(this.src);
	if(this.src.indexOf("-hover") > -1){
		this.src = this.src.replace(/-hover.jpg/, ".jpg");
	}
}
window.onload = function(){
	var images = document.images;
	for(i = 0; i < images.length; i++){
		if(images[i].parentNode.parentNode.parentNode.parentNode.id == "botonera"){
			images[i].onmouseover = rollOver;
			images[i].onmouseout = rollOut;
		}
	}
}