Examine source code of Gray gradient

{
  "theme": {
    "images": {
      "theme_frame": "gray_fabric.jpg"
    },
    "colors": {
      "frame": "#ff6600",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Gray gradient",
  "manifest_version": 2,
  "description": "Simple gradient on gray fabric style"
}