Examine source code of VK Sidebar

{
  "manifest_version": 2,
  "name": "VK Sidebar",
  "description": "Displays VK in a sidebar.",
  "version": "1.0.1",
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "54.0a1"
    }
  },
  "sidebar_action": {
    "default_icon": "icons/vk.png",
    "default_title": "VK",
    "default_panel": "sidebar/panel.html"
  }
}