title: dropdown closes on focus
body: <p>I want to trigger dropdown open on focus on input field.
  But it openes and suddenly closes every time I focus.
  With button toggle everything is ok.
  Here is example:
  <a href="http://codepen.io/piernik/pen/ByKRwE" rel="nofollow">http://codepen.io/piernik/pen/ByKRwE</a></p>
  
  <p>Here is HTML</p>
  
  <pre><code>&lt;div class="input-group"&gt;
      &lt;input type="text" class="form-control" ng-focus="show($event)"&gt;
  
      &lt;div class="input-group-addon"&gt;&lt;i class="fa fa-fw fa-calendar"&gt;&lt;/i&gt;&lt;/div&gt;
  &lt;/div&gt;
  &lt;a class="btn btn-default" ng-click="toggleDropdown($event)"&gt;toggle&lt;/a&gt;
  
  &lt;div class="dropdown" dropdown is-open="model.open"&gt;
      &lt;ul class="dropdown-menu" role="menu"&gt;
          Content
      &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And JS:</p>
  
  <pre><code>$scope.model = {
                  open: false
              };
              $scope.toggleDropdown = function ($event) {
                  $event.preventDefault();
                  $event.stopPropagation();
                  $scope.model.open = !$scope.model.open;
              };
              $scope.show = function ($event) {
                  $event.preventDefault();
                  $event.stopPropagation();
                  $scope.model.open = true;
              };
              $scope.hide = function ($event) {
                  $event.preventDefault();
                  $event.stopPropagation();
                  $scope.model.open = false;
              };
  </code></pre>