title: How to get a WPF Viewbox coefficient of scaling applied
body: <p>In case we use WPF (Silverlight) <code>Viewbox</code> with <code>Stretch="UniformToFill"</code> or <code>Stretch="Uniform"</code> when it preserves content's native aspect ratio, <strong>how could we get knowing the current coefficient of scaling which were applied to the content?</strong></p>
  
  <p>Note: we not always know the exact initial dimensions of the content (for example it's a Grid with lots of stuff in it).</p>