function new_window(ifile,ix,iy,ititle)
{
  
  LeftPosition = (screen.width) ? (screen.width-ix)/2 : 0;
  TopPosition = (screen.height) ? (screen.height-iy)/2 : 0;
  win = window.open(ifile,"Dominio","top="+TopPosition+",left="+LeftPosition+",width="+ix+",height="+iy+",menubar=no,toolbar=no,scrollbars=yes");
}