Add event in __menu template

<nav>
    <ol class="boxMenu">
        {foreach from=$menuItemNodeList item=menuItemNode}
            <li class="{if $menuItemNode->isActiveNode()}active{/if}{if $menuItemNode->hasChildren()} boxMenuHasChildren{/if}">
                <a href="{$menuItemNode->getURL()}" class="boxMenuLink"{if $menuItemNode->isExternalLink()}{if EXTERNAL_LINK_REL_NOFOLLOW} rel="nofollow"{/if}{if EXTERNAL_LINK_TARGET_BLANK} target="_blank"{/if}{/if}>
                    <span class="boxMenuLinkTitle">{lang}{$menuItemNode->title}{/lang}</span>
                    {if $menuItemNode->getOutstandingItems() > 0}
                        <span class="boxMenuLinkOutstandingItems badge badgeUpdate">{#$menuItemNode->getOutstandingItems()}</span>
                    {/if}
                </a>
                
                {if $menuItemNode->hasChildren()}<ol class="boxMenuDepth{@$menuItemNode->getDepth()}">{else}</li>{/if}
                    
                {if !$menuItemNode->hasChildren() && $menuItemNode->isLastSibling()}
                    {@"</ol></li>"|str_repeat:$menuItemNode->getOpenParentNodes()}
                {/if}
        {/foreach}
    </ol>
</nav>