I've got this script working for grabbing and scrolling a website, and it's perfect; the only problem is I'd like to disable it when clicking a form (basically, not being able to drag scroll when clicking inside a form or input tag). This could be either by specifying a class or ID, whatever works best.

This is the script, in case the website goes down or something:

Code:
<script type="text/javascript">

document.onmousedown = function(){
  var e=arguments[0]||event;
  var x=document.body.scrollLeft+e.clientX;
  var y=document.body.scrollTop+e.clientY;
  document.onmousemove=function(){
    scrollTo(x-e.clientX, y-e.clientY);
    return false;
  }
  document.onmouseup=function(){
    document.onmousemove=null;
  }
  return false;
}
</script>
Also, would there be a way to enable grab scrolling just on the background? I mean, disabling it on images, text and any other element, and just leaving the empty spaces of the website with the ability to scroll.

Thanks a bunch in advance.