title: How to add a navigation bar at once for all screen?
body: <p>I would like to ask a question in Titanium mobile. I am finding the way to add one custom navigation bar to all the screens in my project. Currently,I can't find any way to do it. for each window now, I do like this:</p>
  
  <pre><code>win.barImage='images/navigation.png';
  </code></pre>
  
  <p>I don't wish to do: </p>
  
  <pre><code>`win2.barImage='images/navigation.png';`
  win3.barImage='images/navigation.png';
  </code></pre>
  
  <p>for all the screens. This is kinda trouble some, I want to find the way to add just once.</p>