function mostra(evt, msg){
   if(navigator.appName == 'Netscape'){
        x =(evt.layerX); y=(evt.layerY);
   }else {
         x = (evt.x);
        y = (evt.clientY + document.body.scrollTop+ document.documentElement.scrollTop);
   }
   
   var obj = document.getElementById(msg);
   if(obj != undefined){
       obj.style.visibility = 'visible';
       obj.style.top = y-70;
       obj.style.left = x-100;
 //    obj.innerHTML = "<font color='#000000' size='5'>"+msg+"</font>";
   }

}
function tira(msg){
   var obj = document.getElementById(msg);
if(obj != undefined) obj.style.visibility = 'hidden';

}