Examine source code of Flus

{
  "manifest_version": 3,
  "name": "Flus",
  "version": "1.1.1",
  "description": "Collect, organise, annotate on and share links from around the Web.",
  "homepage_url": "https://flus.fr",
  "browser_specific_settings": {
    "gecko": {
      "id": "{4f83b8ac-d692-44f8-9a5d-d018c9865bea}"
    }
  },
  "icons": {
    "48": "icon-48.48f91fe5.png",
    "96": "icon-96.67aee606.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "host_permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "action": {
    "default_icon": "icon-32.7528cbe1.png",
    "default_title": "Flus",
    "default_popup": "popup.2f28d004.html"
  },
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+1"
      }
    },
    "_execute_sidebar_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+2"
      },
      "description": "Open Flus in the sidebar"
    }
  },
  "sidebar_action": {
    "default_icon": "icon-32.7528cbe1.png",
    "default_panel": "sidebar.6f2a59fa.html",
    "default_title": "Flus"
  }
}