Examine source code of Sky Abstract

{
  "theme": {
    "images": {
      "theme_frame": "tema_arriba.jpg"
    },
    "colors": {
      "frame": "#808080",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Sky Abstract",
  "manifest_version": 2,
  "description": "My first theme created with Gimp in twenty minutes. This an abstract theme with blue and white."
}