title: Import XML calues to WPF dropdown
body: <p>I work on a Powershell script for a user management.
  Until now, we used window.form as gui syntax, but we would like to move on to xaml syntax.
  In our gui, we have several dropdown menues which are populated from an external xml file. 
  Those dropboxes are depenting on each other. Whatever you choose in dropdown 1 results in other choices in the second menue.</p>
  
  <p>Example XML (as "c:\data.xml"):</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;GUI&gt;
      &lt;A&gt;
          &lt;1 Name="1" Value="1" /&gt;
          &lt;1 Name="2" Value="2" /&gt;
          &lt;1 Name="3" Value="3" /&gt;
      &lt;/A&gt;
      &lt;B&gt;
          &lt;1 Name="4" Value="4" /&gt;
          &lt;1 Name="5" Value="5" /&gt;
          &lt;1 Name="6" Value="6" /&gt;
      &lt;/B&gt;
  &lt;/GUI&gt;
  </code></pre>
  
  <p>The first Dropdown should contain A or B, the second one should contain either 1-3 or 4-6, according to the choice of the first one. The second one may be faded out until first one is selected (nice to have addition).</p>
  
  <p>As far as I found out until now, all content of the xaml layout must be declared either in the xaml-part or later by changing variables redirecting to the coresponding xaml-name (done that by changing the content of a label). 
  But I could not understand, how I can populate those dropdowns on first use. maybe I am just confused with all those new syntax.</p>
  
  <p>Can anyone please help me out with this one? </p>
  
  <p>Add: I anyone have a easy and understandable tutorial for WPF, I would be glad if you could share it :)
  P.S. English is not my native tongue so please have mercy with my language :/</p>