[jQuery] - select multiple options - back to right position

[jQuery] - select multiple options - back to right position

<div dir="ltr">Hi Folks
After read this cool article <a href="http://css.dzone.com/news/easy-multi-select-transfer-jqu">http://css.dzone.com/news/easy-multi-select-transfer-jqu</a>
I add double click to move option between "select multiple" box.
<script type="text/javascript">
    function doubleclick() {
      $(".cat1 option").dblclick(function() {
        $(this).remove().appendTo('.cat2');
            $(".cat2 option").dblclick(function() {
                var value = $(this).attr('value');   
                $('.cat2 option:selected').remove().appendTo('.cat1'); <=== Here
                doubleclick();
            });
   
      });
    }
</script>
<script type="text/javascript">$(document).ready(function(){   
    doubleclick();
});</script>
Now I want back the element to to right position in '.cat1'
So in "<=== Here" you can see I .appendTo('.cat1') so the element go to the end of select box 'cat1'
<select multiple class="cat1">
    <option value="1">my1</option>
    <option value="2">my2</option>
    <option value="3">my3</option>
    <option value="4">my4</option>
    <option value="5">my5</option>
</select>
<select multiple class="cat2"></select>
We can put my2,my3,my4 inside cat2 and back my3 to cat1 so my3 need be after my1. (of course I will have much more elements)
var value = $(this).attr('value'); was the begin of my journey....
So ideas?
Regards
Mario
macm
</div>