Don't understand Event.addBehavior for filter-menu

[Togg]

Can someone please explain how the javascript event action is
activated for the filter-menu?

I saw in hobo-rapid.js that a event is added to form.filter-menu, but
I couldn't trace down how its finally got activated.
The problem is when I add a own filter-menu item, it doesnt activate
the event.

This is what I have in my index.dryml:

<form action="&request.request_uri" class="filter-menu"
method="get"><div class="hidden-fields"></div>
<div>
<select name="show">
<option value="">All</option>
<option value="complete">Complete</option>
<option value="incomplete">Incomplete</option>
</select>
</div>
</form>

How can I activate the Event.addBehaviour for this filter-menu?
Maybe someone also knows how to use a enum in the filter-menu options
to prevent writing everything again...


Thanks,
Sebastian