title: Canvas's children and canvas's border overlap
body: <p>I have a canvas placed into a grid. And the grid is placed into a border. When I draw some item (a white line for instance) on the canvas, this item lays over the border, so the border is erasing. Does anybody know how I can avoid it? I tried to set margin to the canvas, larger border's size than the canvas's one, but nothing helps.</p>
  
  <p>This is my xaml:</p>
  
  <pre><code>&lt;Border BorderThickness="1"  BorderBrush="#333333" Opacity="1" Name="inner_canvas_border"&gt;
      &lt;Grid Name="grid1"&gt;
          &lt;Canvas Name="Canvas1"HorizontalAlignment="Center" VerticalAlignment="Center" Width="700" Height="450" /&gt;
      &lt;/Grid&gt;
  &lt;/Border&gt;
  </code></pre>