title: NativeScript: change background color and text of a Button belonging to a ListView
body: <p>I need a 2-state toggle Button: at each tap, that changes its background color and its text label (color and text). Its implementation is simple and it works correctly when the button belongs to a simple page. 
  Instead, when the button is put in each element of a simple list (20 elements) it does not change its background color, and only its label text changes, not its color.</p>
  
  <p>Here some code details to check the problem:</p>
  
  <pre><code>&lt;StackLayout orientation="vertical" &gt;
      &lt;ListView items="{{ items }}" itemTap="onItemTap"&gt;
          &lt;ListView.itemTemplate&gt;
              &lt;StackLayout orientation="vertical" class="follow-button"&gt;
                  &lt;Button text="Undefined" tap="onTap"/&gt;
              &lt;/StackLayout&gt;
          &lt;/ListView.itemTemplate&gt;
      &lt;/ListView&gt;
  &lt;/StackLayout&gt;   
  </code></pre>
  
  <p>and in js side ('value' not binded to a button, is used here only to demonstrate tap problem on a single button of the list):</p>
  
  <pre><code>var value = 1;
  exports.onTap = function (args) {
      view  = args.object;
      value = value === 1 ? 0 : 1;
      view.text            = value === 1 ? "button on" : "button off";
      view.backgroundColor = value === 1 ? "red"       : "white";
      view.color           = value === 1 ? "white"     : "red";
  }
  </code></pre>
  
  <p>I see that removing or fixing the text then background changes correctly at each tap.</p>
  
  <p>Any suggestion?</p>