title: WP7 Max width textbox and position to set from right
body: <p>I have this code:</p>
  
  <pre><code>&lt;controls:PivotItem Header="Hledat"&gt;
      &lt;Canvas Margin="0"&gt;
          &lt;TextBox  Name="SearchTxb"  Height="72" Text="" VerticalAlignment="Top" HorizontalAlignment="Right" /&gt;
          &lt;Button Name="SearchBtn" Margin="0,74,100,0" Width="200" Height="72" Click="SearchBtn_Click" HorizontalAlignment="Right" VerticalAlignment="Top"&gt;Hledat&lt;/Button&gt;
      &lt;/Canvas&gt;
  &lt;/controls:PivotItem&gt;
  </code></pre>
  
  <p>and I want to support Portrait and Landscape. This should be pivotitem for search. I want to textbox to change width to full size of phone screen and I want to button set position to f.e. 20 from right side. What should I add to code? Thanks</p>