title: WPF Grid horizontalalignment doesn't work. Sizes don't changes
body: <p>I have a Stack and I have a Grid inside of Stack.</p>
  
  <p>I need to increase Stack and Grid sizes when I resize the window.
  I set Stack and Grid HorizontalAlignment to 'Stretch'</p>
  
  <p>Stack works fine but grid sizes don't raises when I resize the window</p>
  
  <p>This is my code.</p>
  
  <pre><code>&lt;StackPanel Background="Blue" Orientation="Horizontal" HorizontalAlignment="Stretch" Grid.Column="1" Margin="13,0,0,0" &gt;
     &lt;Grid HorizontalAlignment="Stretch" Background="Beige" Width="515"&gt;
  
          &lt;Grid.RowDefinitions&gt;
              &lt;RowDefinition Height="100" /&gt;
              &lt;RowDefinition Height="240" /&gt;
              &lt;RowDefinition Height="100" /&gt;
          &lt;/Grid.RowDefinitions&gt;
  
          &lt;Image x:Name="imageMap" Source="Resources/images.jpg" HorizontalAlignment="Stretch" Grid.Row="0" Stretch="Fill" Margin="0,0,0,0" /&gt;
  
     &lt;/Grid&gt;
  &lt;/StackPanel&gt;
  </code></pre>
  
  <p>Please advise</p>