title: Updating an extension button dynamically - inspiration required
body: <p>I am building an extension where I want to be able to add a signifier to the extension button when the extension in the code has been activated.  I was hoping I could add text to the extension button (top right)</p>
  
  <p>Here is a simple scenario.  Let's say my extension monitors browsing and gets the tab url, in my extension I have a list of domains to watch for.</p>
  
  <p>Watch for these domains
  www.website1.com
  www.website2.com</p>
  
  <p>If a user visits a domain in the watched list I want to indicate this somehow, by adding some text somewhere - I was hoping in the top right of the browser where the extensions buttons are.  I don't really want to use a notification window as I want something unobtrusive.  The text that I want to display would just be a few letters but different for different urls.</p>
  
  <p>Does anyone have any inspiration?</p>
  
  <p>Thanks</p>