title: Adding drop-down menu to chrome extension icon
body: <p>I know that I can associate a <em>popup.html</em> to clicks on the extension button. However, I want it to be a menu, like the one popping up after clicking on Chrome's own "Customize and control Google Chrome" button (located to the right of your extension icons). I tried to Google it but no one seemed to be talking about that. Am I missing any <em>common sense</em> about Chrome extension development?</p>