The system uses a right box of selected items populated from a record which
may be removed or sorted.
The left box of items is populated by the remaining options not currently
held in the record. An item may only be either in or out of the record (ie
left or right).

Everything works fine except for one problem with the add or remove feature:

 I can not seem to create a new option in a particular select box.

eg removing from the right and putting on the end of the left does not work:
selectboxleft.options[lengthofleft] = selectboxright.options[i]
(or a modified version to replace the value and text seperately)

But  replacing an existing option does work:
eg options[lengthofleft-1]  will put the value to remove across to the left
by replacing the last value on the left

Does anyone know if it is actually possible to create new options once a
select box is written?

Many thanks

Jon Shaw

The following works fine in IE5.5, and should also be fine in IE5.0.
Since it's pure DOM, it should also work just fine in NN6, though I
didn't test that...

<script>
function MoveOption(x){
    var y=x[x.selectedIndex], c=y.cloneNode(true);
    y.parentNode.removeChild(y);
    y=document.getElementById('Sel1');
    // Next line positions moved option 1st...
    y.insertBefore(c,y.options[0]); y.options[0].selected=true;
        // Or, substitute next line to position last instead...
        // y.appendChild(c); c.selected=true;
    if (x.length<2) x.parentNode.removeChild(x)}
</script>

<p><select id="Sel1">
<OPTION value="cR">Red</OPTION>
<OPTION value="cY">Yellow</OPTION>
<OPTION value="cB">Blue</OPTION>
</select></p>

<p><select id="Sel2" onchange="MoveOption(this.options)">
<OPTION>Select...</OPTION>
<OPTION value="fA">Apple</OPTION>
<OPTION value="fP">Peach</OPTION>
<OPTION value="fG">Grape</OPTION>
</select></p>

- Peter