title: How can I avoid the empty space of a bloc not displayed?
body: <p>I have to display or hide two outputpanels according to the selected radiobutton as you can see in the following code : </p>
  
  <pre><code>&lt;p:outputLabel style="width:20%" value="Time unit"&gt;&lt;/p:outputLabel&gt;
  &lt;p:selectOneRadio style="width:34%;margin-left:20%" id="choix" value="#{graphe.choix_aff}"&gt;
      &lt;f:selectItem itemLabel="Month" itemValue="mois" /&gt;
      &lt;f:selectItem itemLabel="Day" itemValue="jour" /&gt;
      &lt;f:selectItem itemLabel="Hour" itemValue="heure" /&gt;
      &lt;p:ajax update="panel1,panel2"  listener="#{graphe.handleChange}" /&gt;
  &lt;/p:selectOneRadio&gt;  
  
  &lt;p:outputPanel id="panel1"&gt;
      &lt;p:calendar style="width:600px" rendered="#{graphe.display_cal()}" id="popup1" value="#{graphe.date1}"&gt;
      &lt;/p:calendar&gt;
  &lt;/p:outputPanel&gt;  
  
  &lt;p:outputPanel id="panel2"&gt;
      &lt;p:calendar style="width:600px" id="t" value="#{graphe.date3}" pattern="MM/dd/yyyy HH" rendered="#{graphe.display_h()}"&gt;
      &lt;/p:calendar&gt;
  &lt;/p:outputPanel&gt;
  </code></pre>
  
  <p>If I choose the option 'Hour', the calendar (panel2) will be shown after some empty lines (those of the panel1).</p>
  
  <p>How can I solve this problem ?
  Thank you.</p>