window.onError=null;
var cop1 = new Image(100,100) ;
	cop1.src = "img/entrasito.gif" ;
var cop2 = new Image(100,100) ;
	cop2.src = "img/entrasito3.gif" ;
function a_cop() { document.images[1].src=cop2.src; }
function b_cop() { document.images[1].src=cop1.src; }