Setting up choice of forum style elsewhere on page?

[I, Brian]

I've set up 2 different styles - one narrow, and one broad.

I've tried to move the dropdown option menu to choose between the styles to the left-hand nav, as here:
http://www.platinax.co.uk/forum/

However, although I can select an option, it doesn't actually do anything - ie, the alternative style does not load up.

I've currently got the following code in my left-hand navigation that I thought would allow style selection there:

<form action="$vboptions[forumhome].php" method="get">

        <div style="width:$stylevar[outerdivwidth]" align="$stylevar[left]">
    

    <if condition="$show['quickchooser']">

            <select name="styleid" id="ressel" onchange="switch_styleid(this)">
                    $quickchooserbits
            </select>
    </if>

        </div>
</form>

Any suggestions on how to make this work are warmly welcomed.