[PhilJ]

v4.x - Up to 5 levels... ensure Modules > Flyout Menus is enabled + 'Cache the menu' is disabled.

<ul>
{foreach from=$categories_menu_list item=c}
<li><a href="home.php?cat={$c.categoryid}">{$c.category}</a>
    {if $c.childs}
    {foreach from=$c.childs item=sc name=sc}
    {if $smarty.foreach.sc.first}<ul>{/if}
    <li><a href="home.php?cat={$sc.categoryid}">{$sc.category}</a>
        {if $sc.childs}
        {foreach from=$sc.childs item=ssc name=ssc}
        {if $smarty.foreach.ssc.first}<ul>{/if}    
        <li><a href="home.php?cat={$ssc.categoryid}">{$ssc.category}</a>
            {if $ssc.childs}
            {foreach from=$ssc.childs item=sssc name=sssc}
            {if $smarty.foreach.sssc.first}<ul>{/if}    
            <li><a href="home.php?cat={$sssc.categoryid}">{$sssc.category}</a>
                {if $sssc.childs}
                {foreach from=$sssc.childs item=ssssc name=ssssc}
                {if $smarty.foreach.ssssc.first}<ul>{/if}    
                <li><a href="home.php?cat={$ssssc.categoryid}">{$ssssc.category}</a></li>
                {if $smarty.foreach.ssssc.last}</ul>{/if}
                {/foreach}
                {/if}
            </li>
            {if $smarty.foreach.sssc.last}</ul>{/if}
            {/foreach}
            {/if}
        </li>
        {if $smarty.foreach.ssc.last}</ul>{/if}
        {/foreach}
        {/if}
    </li>
    {if $smarty.foreach.sc.last}</ul>{/if}
    {/foreach}
    {/if}
</li>
{/foreach}
</ul>