title: ionic Back button incorrectly shown while switching tabs
body: <p>I have a main tab, which just shows the list of items. and settings tab which has nested view for setting different configs.</p>
  
  <p>If I navigate in this particular order, the back button is shown incorrectly, or if it is to be shown, the title doesn't get left: 37px</p>
  
  <p>This is how I am creating the nav bar.</p>
  
  <pre><code>&lt;ion-nav-bar class="bar-stable no-animation" align-title="left"&gt;
    &lt;ion-nav-back-button class="button-icon icon ion-ios7-arrow-back"&gt;&lt;/ion-nav-back-button&gt;
  &lt;/ion-nav-bar&gt;
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/yfrdu.png" alt="enter image description here"></p>
  
  <p>Is there a solution, either to clear the history of that tab, so while clicking back on it opens the main settings tab instead of the previously opened nested view? Or if it needs to be shown, it should properly calculate the left of title.</p>
  
  <p>Here's a <a href="http://codepen.io/anon/pen/ECyxA" rel="nofollow noreferrer">codepen</a> demo. Click on tabs in this order.</p>
  
  <pre><code>1. On main page, click on Scientific Facts
  2. After view changes, click on Contacts tab
  3. Then click on Home tab again. It reproduces the behavior.
  </code></pre>
  
  <p>Update:</p>
  
  <p>So far what I found is that there's a <code>$scope.$watch</code> which is deciding whether to show or hide back button. and this gets triggered late (after calculation and alignment of title). Hence the while calculating, <code>leftWidth</code> doesn't get back button's width.</p>