Examine source code of Sidebar Clock

{
  "manifest_version": 2,
  "name": "Sidebar Clock",
  "version": "1",
  "browser_specific_settings": {
    "gecko": {
      "id": "sidebar-clock@menhera.org"
    }
  },
  "author": "Menhera.org",
  "homepage_url": "https://github.com/menhera-org/sidebar-clock",
  "description": "Simple Sidebar Clock for Firefox",
  "permissions": [],
  "incognito": "spanning",
  "sidebar_action": {
    "browser_style": true,
    "default_icon": {
      "16": "sidebar-clock.png",
      "32": "sidebar-clock.png"
    },
    "default_panel": "sidebar.html"
  },
  "icons": {
    "48": "sidebar-clock.png",
    "96": "sidebar-clock.png"
  }
}