jQuery: hidden elements are considered "visible", why?
<p>I've made a working example of what I want:</p>

<p><a href="http://jsfiddle.net/uRhuK/" rel="nofollow">http://jsfiddle.net/uRhuK/</a></p>

<p>Try to click on one line:</p>

<ul>
<li>Aujourd'hui (lundi 5 mars)</li>
<li>Demain (mardi 6 mars)</li>
<li>Après demain (mercredi 7 mars)</li>
<li>Vendredi 8 mars</li>
<li>Un autre jour</li>
</ul>

<p>Then try to click on another line: it works great: it hide the previous and shows the new one.</p>

<p>Now try to re-click on the first line: nothing happens! Why?</p>

<p>Because that code is ok = the element is considered visible:</p>

<pre><code>if ($(id).is(':visible')) {
    return;
}
</code></pre>

<p>This would mean that after one slideUp() the element is considered visible.</p>

<p>Any idea how comes?</p>

<p>[edit]</p>

<p>I've changed my code so now it work here: <a href="http://jsfiddle.net/uRhuK/2/" rel="nofollow">http://jsfiddle.net/uRhuK/2/</a> but I don't know if it's clean jQuery code or not.</p>
