Examine source code of DragFactor

{
  "theme": {
    "images": {
      "theme_frame": "dragfactor_for_firefox.jpg"
    },
    "colors": {
      "frame": "#918e8e",
      "tab_background_text": "#f7f4f4"
    }
  },
  "version": "2.0",
  "name": "DragFactor",
  "manifest_version": 2,
  "description": "Based on my DragFactor website"
}