title: Dropdown Button in UWP
body: <p>I'm unable to use the <code>DropDownButton</code> in my UWP app. Is there an extension or reference that I need to use before the control name?  </p>
  
  <p>If not, is there an alternative of the control?<br>
  I can't use the <code>ComboBox</code> as I need the header text in the button, not above it.</p>