title: caliburn micro update progress bar using task
body: <p>i'm having this problem, been using caliburn micro and i'm trying to update my progress bar. but nothing it's happening.
  i've read a couple of threads in here about it and i'm stuck, it just doesn't update</p>
  
  <p>could you see what's wrong with my code?
  my xaml is this:</p>
  
  <pre><code>&lt;ProgressBar x:Name="PbEstadoConfig" FlowDirection="LeftToRight" Width="200" Height="30" Margin="6,0,572,0"&gt;
  </code></pre>
  
  <p>and in my view model i have the following code:</p>
  
  <pre><code>private double _pbEstadoConfig;
              public double PbEstadoConfig
              {
                  get { return _pbEstadoConfig; }
                  set
                  {
                      _pbEstadoConfig = value;
                      NotifyOfPropertyChange(() =&gt; PbEstadoConfig);
                  }
              }
  
       public void Seguinte()
              {
                  var t = Task.Factory.StartNew(() =&gt;ActualizaPB("seguinte"));
  
  
              }
      protected void ActualizaPB(string value){
       PbEstadoConfig += 20.0;
  
  }
  </code></pre>