title: In XAML how to say: default width and height for e.g. TextBox
body: <p>So I'm coming at WPF from a HTML perspective.</p>
  
  <p>I just want to put a <code>TextBox</code> on my Window like this:</p>
  
  <pre><code>&lt;Grid&gt;
      &lt;TextBox Name="theName" /&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>Turns out that the <code>TextBox</code> is then HUGE, covers the whole window. (!)</p>
  
  <p>Ok, that's not what I want, but I don't want to define the EXACT size either since I know <code>Height</code> and <code>Width</code> should be flexible, so I try:</p>
  
  <pre><code>&lt;TextBox Name="theName" Width="Auto" Height="Auto"/&gt;
  </code></pre>
  
  <p>Same thing. So I try:</p>
  
  <pre><code>&lt;TextBox Name="theName" 
      HorizontalAlignment="Stretch" 
      VerticalAlignment="Stretch"/&gt;
  </code></pre>
  
  <p>Same thing. So I just hard code the sizes:</p>
  
  <pre><code>&lt;TextBox Name="theName" Width="100" Height="20"/&gt;
  </code></pre>
  
  <p>Which I know is not a good programming practice in WPF.</p>
  
  <p>So, what how do you tell <code>TextBox</code> to "display default sizes for the font size being used"?</p>