function popup(url,windowname,width,height,features) { 

width=(width)?width:screen.width/2; 
height=(height)?height:screen.height/2; 
var screenX = (screen.width/2 - width/2); 
var screenY = (screen.height/2 - height/2); 
var features= "width=" + width + ",height=" + height +",scrollbars=auto,status=no"; 
features += ",screenX=" + screenX + ",left=" + screenX; 
features += ",screenY=" + screenY + ",top=" + screenY; 

var mywin=window.open(url, windowname, features); 
if (mywin) 
mywin.focus(); 
return mywin; 
}

function popup2(url,windowname,width,height,features) { 

width=(width)?width:screen.width/2; 
height=(height)?height:screen.height/2; 
var screenX = (screen.width/2 - width/2); 
var screenY = (screen.height/2 - height/2); 
var features= "width=" + width + ",height=" + height +",scrollbars=yes,status=no,resizable=yes"; 
features += ",screenX=" + screenX + ",left=" + screenX; 
features += ",screenY=" + screenY + ",top=" + screenY; 

var mywin=window.open(url, windowname, features); 
if (mywin) 
mywin.focus(); 
return mywin; 
}

function desplegaMenu(mostra) {
var e = document.getElementById("mano_de_obra");
if (mostra == true) {
e.className = "menu_obert";
}
else {
e.className = "menu_tancat";	
}
}