title: How to cast from Double to GridLength? C#
body: <p>I'm trying to get the value of a GridRow[0] and  its parent (Stackpanel), then I'm substracting the value of GridRow[0] of Stackpanel value. 
  The last step for  me is assign the result to GridRow[1].</p>
  
  <pre><code>gridLengthVariable  = othergridLengthVariable - doubleVariable;
  </code></pre>
  
  <p>In this case I can't do a explicit conversion from Double to GridLength</p>
  
  <pre><code>gridLengthVariable.Value
  </code></pre>
  
  <p>Is a readable only property so I can't assign here. </p>
  
  <p>I need one way to cast double to gridLength although I'm open minded to make deeper changes in my code if this bring me the same solution. </p>
  
  <p>XAML changes can't be done.</p>
  
  <p>EDIT: </p>
  
  <p>I will show what I'm trying to do:</p>
  
  <p>It's a dynamic change of a XAML created gridRow. </p>
  
  <pre><code>     gridProfile.RowDefinitions[1].Height =  
       stackPanelProfile.Height -  gridProfile.RowDefinitions[0].Height;
  </code></pre>
  
  <p>Here I can't apply operator "<strong>-</strong>"</p>
  
  <p>Thanks.</p>