title: Submit Login control button when I hit Enter
body: <p>I have an ASP.NET web page with a Login control on it.  When I hit Enter, the Login button doesn't fire; instead the page submits, doing nothing.</p>
  
  <p>The standard solution to this that I've found online is to enclose the Login control in a Panel, then set the Panel default button.  But apparently that doesn't work so well if the page has a master page.  I've tried setting the default button in code with <em>control</em>.ID, <em>control</em>.ClientID, and <em>control</em>.UniqueID, and in each case I get:</p>
  
  <blockquote>
    <p>The DefaultButton of panelName must be the ID of a control of type IButtonControl.</p>
  </blockquote>
  
  <p>I'm sure there's a way to do this with JavaScript, but I'd really like to do it with plain old C# code if possible.  Is it possible?</p>