title: Press-and-hold right-click conflicts with Manipulation events
body: <p>I'm using the <code>Manipulation</code> events (<code>IsManipulationEnabled</code>, <code>ManipulationDelta</code>, etc) to move and zoom an image. This works fine. I also want to use right-click to create a rectangle of selection to define a zone (drag and drop, the usual way, only with right-click) on the image. It works fine using the mouse on both touch (Surface) and non-touch (Win 7) devices. Though, when "right-clicking" on the Surface (therefore tap and hold with a finger), I see the typical little square appearing, but when I move my finger after that, it moves the image, instead of drawing the rectangle. It looks as if the <code>Manipulation</code> events have priority over the "finger right click". What am I doing wrong ?</p>
  
  <pre><code> &lt;Grid
      Name="theGrid"
      MouseMove="OnMouseMove"
      MouseRightButtonUp="theGrid_MouseRightButtonUp"
      MouseRightButtonDown="theGrid_MouseRightButtonDown"
      Background="Black"&gt;
  
      &lt;Rectangle Name="RectangleContainingBackgroundImage"
                 IsManipulationEnabled="True"
                 RenderTransform="{Binding Path=ImageTransform}"&gt;
          &lt;Rectangle.Fill&gt;
              &lt;ImageBrush x:Name="BackgroundImage" Stretch="Uniform"/&gt;
          &lt;/Rectangle.Fill&gt;
      &lt;/Rectangle&gt;
  </code></pre>
  
  <p>At start :</p>
  
  <pre><code>ScreenTouchManager touchManager = new ScreenTouchManager(this.theGrid);
  this.RectangleContainingBackgroundImage.ManipulationStarting += touchManager.Image_ManipulationStarting;
  this.RectangleContainingBackgroundImage.ManipulationDelta += touchManager.Image_ManipulationDelta;
  this.DataContext = touchManager;
  </code></pre>
  
  <p>In ScreenTouchManager :</p>
  
  <pre><code>public void Image_ManipulationStarting(object sender, ManipulationStartingEventArgs e)
  {
      // Ask for manipulations to be reported relative to the grid
      e.ManipulationContainer = this.ManipContainer; // MC = constructor param
  }
  </code></pre>
  
  <p>Thank you.</p>