Someone

{% for gallery in galleries %}

<option value="{{ gallery.id }}"{% ifequal gallery.id request.session.gallery %} selected="selected"{% endifequal %}>{{ gallery.name|escape }}</option>
<!-- {{ gallery.id }} {{request.session.gallery }} -->

{% endfor %}

outputs:

<select name="gallery">
	<option value="-">---</option>
	<option value="1">Stupid gallery</option><!-- 1 2 -->
	<option value="2">acff</option><!-- 2 2 -->
	<option value="3">kndo</option><!-- 3 2 -->
</select>