title: CKEditor Custom Plugins Button
body: <p>I've written a custom plugin for CKEditor--successful on all fronts, save one currently:  I can't, for the life of me, figure out how to customize the image on the button in the toolbar of the editor.  As I'm a new user, you'll have to click through to see attached image; the highlighted square in the top left should have a pretty picture (like most of the other toolbar items).</p>
  
  <p><img src="https://i.stack.imgur.com/CYg4y.jpg" alt="Screenshot"></p>