title: Open a context menu via command binding
body: <p>I'm trying to bind a button to open its context menu on a left click. I'm aware how to do this programmatically, but is there a way to do this with a default command binding?</p>
  
  <p>I've currently got:</p>
  
  <pre><code>    &lt;Button Command="ApplicationCommands.ContextMenu"&gt;
          &lt;Button.ContextMenu&gt;
              &lt;ContextMenu&gt;
                  &lt;MenuItem ...
  </code></pre>
  
  <p>but no such luck... if I do this then the button is disabled. I guess this indicates that the command cannot be executed, but why?</p>