function mouseUp(evt)
{
  draggedBox = null;
}

function mouseMove(evt)
{
  var coords = mousePos(evt);

  if(draggedBox){
    draggedBox.style.position = "absolute";
    draggedBox.style.top = (coords.y - offset.y) + "px";
    draggedBox.style.left = (coords.x - offset.x) + "px";
    return false;
  }
}