title: Change WPF DocumentViewer viewing mode
body: <p>Hello I've got the problem that when I just add a <code>&lt;DocumentViewer x:Name="docViewer" /&gt;</code> I get a toolbar what allow me to change the viewing mode of the XPS document like here:
  <img src="https://i.stack.imgur.com/U30kW.png" alt="enter image description here"></p>
  
  <p>But how can I do this programmatically?
  I cant find any property that do this and the MSDN and Google say nothing about this feature.
  Then I found the <code>FlowDocumentReader</code> control what have a <code>ViewingMode</code> property, however it can't display a XPS document. I can't believe that it is not possible to do this, I mean that function is available by default, I just want to change it programmatically...</p>