title: Angular 2 make function available in ng-content
body: <p>I have a dropdown with a template like this:</p>
  
  <pre><code>&lt;div class="dropdown-trigger" (click)="contentToggle()"&gt;
       &lt;ng-content select="dropdown-trigger"&gt;&lt;/ng-content&gt;
  &lt;/div&gt;
  &lt;div class="dropdown-content" *ngIf="showContent"&gt;
       &lt;ng-content select="dropdown-content"&gt;&lt;/ng-content&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I'd like to be able to use <code>contentToggle()</code> in whatever I put in the <code>ng-content</code> so that I can have additional elements that can be used to close the dropdown, for example I might want a close button... What's the best way to do this? </p>