Examine source code of Developer 2.0

{
  "theme": {
    "images": {
      "theme_frame": "black-1.jpg"
    },
    "colors": {
      "frame": "#333333",
      "tab_background_text": "#f1f1f1"
    }
  },
  "version": "2.0",
  "name": "Developer 2.0",
  "manifest_version": 2,
  "description": "A simple black gradient header with a solid white Add-on bar. Perfect for developer and other Firefox Add-on's found hiding in the lower bar."
}