Examine source code of Ctrl-background

{
  "manifest_version": 2,
  "author": "Lucius Q. User",
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "main.js"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "description": "Makes Ctrl/Cmd-click not switch focused tab for rel=\"external\" links.",
  "name": "Just let me open background tabs",
  "short_name": "Ctrl-bckgrnd",
  "version": "0.1.1resigned1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{181b7c53-cb4c-4328-aa86-56974d2ada6b}"
    }
  }
}