Examine source code of Bird calling

{
  "theme": {
    "images": {
      "theme_frame": "Bird-calling_h.png"
    },
    "colors": {
      "frame": "#d3d4ff",
      "tab_background_text": "#333333"
    }
  },
  "version": "2.0",
  "name": "Bird calling",
  "manifest_version": 2,
  "description": "I always loved birds. And abstract art. So I married those too :)"
}