function mouseMove (evt) { 
  if (document.layers) {
    x=evt.x; y=evt.y;
  } 
  if (document.all) {
    x=event.clientX; y=event.clientY;
  } else {
    if (document.getElementById) {
      x=evt.clientX; y=evt.clientY; 
    }
  }
} 
var x=0; var y=0;
if (document.layers) 
  document.captureEvents(Event.MOUSEMOVE); 
if (document.layers || document.all) 
  document.onmousemove = mouseMove; 
if (document.addEventListener) 
  document.addEventListener('mousemove', mouseMove, true);