Examine source code of Plain Functional

{
  "theme": {
    "images": {
      "theme_frame": "plainFunctional.png"
    },
    "colors": {
      "frame": "#666666",
      "tab_background_text": "#333333"
    }
  },
  "version": "2.0",
  "name": "Plain Functional",
  "manifest_version": 2,
  "description": "For XP, 4 toolbars, functional separation of toolbars, neutral colors (ideal for XP with plain skin)"
}