title: wpf command parameter from other object
body: <p>I'm wondering how to mark up the XAML for the following.  I have a view model with an object based on <code>ICommand</code>.</p>
  
  <p>I have a form with a textbox and a button.  The button is hooked to the <code>ICommand</code> object via <code>Command="{Binding MyButtonInViewModel}"</code>.</p>
  
  <p>What I want to do is set the button's <code>CommandParameter</code> equal to whatever is in the text of the textbox such as to invoke a "Search", but obviously don't know how to hook across controls in the view.</p>