Examine source code of ShadowFirefox 4

{
  "theme": {
    "images": {
      "theme_frame": "ShadowFirefox4.jpg"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "ShadowFirefox 4",
  "manifest_version": 2,
  "description": "Shadow Firefox 4! Remove menu bar for better result...have fun!"
}