title: WPF: Give to an UserControl a list of sub controls
body: <p>I would like to do(for test and education purpose) a wizard.</p>
  
  <p>At the end, I would like to be able to define it like this:</p>
  
  <pre><code>&lt;Window ...&gt;
      &lt;Wizard&gt;
          &lt;WizardStep&gt;
          ...
          &lt;/WizardStep&gt;
          &lt;WizardStep&gt;
          ...
          &lt;/WizardStep&gt;
          &lt;WizardStep&gt;
          ...
          &lt;/WizardStep&gt;
      &lt;/wizard&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>I don't need skinning or such things, so <code>UserControl</code> is fine for me.</p>
  
  <p>Currently I'm struggling on the <code>Wizard</code> class, how can I make it allowing a list of subcontrols, and how can I use them inside of my <code>UserControl</code></p>