Examine source code of Thunderbird 3

{
  "theme": {
    "images": {
      "theme_frame": "1.jpg"
    },
    "colors": {
      "frame": "#96e5ff",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Thunderbird 3",
  "manifest_version": 2,
  "description": "My first Firefox persona with Thunderbird 3 theme."
}