Drag’n'Drop using Javascript and DHTML

This is a quick tutorial explaining how to insert drag’n'drop events in our html code.
Thanks to Javascript and DHTML, you can write complex
web pages.

This piece must be put in the <head> section:

<script type="text/javascript">
  var MouseDown;
  var OffsetX;
  var OffsetY;
  var ie5=document.all&&document.getElementById;

  function init(e) {
    OffsetX = ie5 ? window.event.clientX : e.clientX;
    OffsetY = ie5 ? window.event.clientY : e.clientY;
    MouseDown = true;
  }

  function done(e) {
    MouseDown = false;
  }

  function windowMove(e) {
    if ((ie5 && MouseDown == true) ||
       ((e != null) && (MouseDown == true))) {

        topX = parseInt (parent.document.
                getElementById ("options").style.left);
        topY = parseInt (parent.document.
                getElementById ("options").style.top);

        parent.document.getElementById ("options") .style.top =
                (topY + (ie5 ? window.event.clientY : e.clientY) -
                OffsetY) + "px";

        parent.document.getElementById ("options").style.left =
                (topX + (ie5 ? window.event.clientX : e.clientX) -
                OffsetX) + "px";
    }
  }
</script>