title: Boolean to Visibility Converter in Win RT XAML not working first time
body: <p>Strange one when working in XAML for Windows RT (windows store app) today, when <code>IsValid=true</code> is set from my view model  my boolean to visibility converter does not work the first time (my path remains hidden), but then does display correctly visibility subsequent times after that.</p>
  
  <p>Is this a bug, or what could be going on?</p>
  
  <p>I want to show my tick on <code>IsValid=true</code> including initial time:</p>
  
  <pre><code>&lt;Path x:Name="MyTick" Data="F1 M 45.12,5.49L 21.255,40.8L 20.4525,40.8L 0,23.2875L 5.775,15.7875L 19.2525,27.3L 37.695,-1.90735e-006L 45.12,5.49 Z " 
  Fill="#FF008500" Grid.Column="1" Width="42" Height="42" Margin="24,12,12,0" 
  Stretch="Fill" VerticalAlignment="Top"  Visibility="{Binding IsValid, Converter={StaticResource BooleanToVisibilityConverter}}" /&gt;
  </code></pre>
  
  <p>resorting to setting the visibility on code behind of the .xaml.cs does work, but this defeats the purpose of MVVM for such a simple operation and I'd prefer not to do it this way.</p>
  
  <p>This problem also occurs on first time of a textblock I need to show/hide on <code>IsValid=true</code> also. First time, it still is collapsed, second time I raise the property changed, it works fine. :S</p>