This question has been answered by Wanze. See the first response.
<a href="[[+url]]" class="[[+cultureKey]][[+active:notempty=` [[+active]]`]]"><img src="pathToTheFlags/[[+cultureKey]].gif" alt="[[+cultureKey]]" class="flag" /></a>
<?php
#flag { position:fixed; top:30px; right:30px; }
[[BabelLinks? &tpl=`MyBabelTpl`]]
<div id="flag">[[BabelLinks? &tpl=`MyBabelTpl`]]</div>