title: Visual Studio 2010 extension get selected text
body: <p>I'm writing my own extension. I've created a toolbar button. The template I used was "Visual Studio Package" and there was an option during the wizard to create a command button (or something like that)</p>
  
  <p>So the button shows up, but I can't work out how to get the current document or the selected text within the document.</p>
  
  <p>Any help would be appreciated.</p>