title: Redecorate ILightweightLabelDecorator
body: <p>I have a working <code>ILightweightLabelDecorator</code> that happily decorates some kind of object in my tree. Now that object changes, and I want to trigger a refresh / redecoration.</p>
  
  <p>I found <a href="http://www.eclipse.org/articles/Article-Decorators/decorators.html" rel="nofollow">this article</a> (under "Re-decorate") which wants me to call
  <code>LabelProvider#fireLabelProviderChanged()</code>. The problem is: the method in question is a protected one and the place where the object changes is nowhere near the label decorator. </p>
  
  <p>Let's say for the sake of simplicity I have the following method on my <code>IViewPart</code>:</p>
  
  <pre><code>public void refresh() {
      this.treeViewer.refresh();
  }
  </code></pre>
  
  <p>How would I trigger the redecoration of my viewer elements there?</p>