function mouseDown(e) {
if (parseInt(navigator.appVersion)>3) {
  var clickType=1;
  if (navigator.appName=="Netscape") clickType=e.which;
  else clickType=event.button;
  if (clickType!=1) {
   alert ('Robba mia ;P nun se tocca')
   return false;
  }
}
return true;
}
if (parseInt(navigator.appVersion)>3) {
document.onmousedown = mouseDown;
if (navigator.appName=="Netscape") 
  document.captureEvents(Event.MOUSEDOWN);
}