{
  "title": "View Page Source Button",
  "name": "mpopp-view-page-source",
  "version": "1.2.1",
  "description": "Adds a View Page Source button to the toolbar",
  "main": "lib/index.js",
  "author": "Markus Popp",
  "icon": "icon.png",
  "engines": {
    "firefox": ">=45.0"
  },
  "license": "MIT",
  "keywords": [
    "jetpack"
  ],
  "preferences": [{
    "name": "openInTab",
    "title": "Open in Tab or Window?",
    "label": "Open in tab or window",
    "description": "Allows to open source code in a new tab (default) or a new window",
    "type": "radio",
    "options": [{
      "label": "Tab",
      "value": true
    }, {
      "label": "Window",
      "value": false
    }],
    "value": true
  }],
  "permissions": {
    "private-browsing": true
  }
}

{
  "title": "View Page Source Button",
  "name": "mpopp-view-page-source",
  "version": "1.2.2",
  "description": "Adds a View Page Source button to the toolbar",
  "main": "lib/index.js",
  "author": "Markus Popp",
  "icon": "icon.png",
  "engines": {
    "firefox": ">=52.0"
  },
  "license": "MIT",
  "keywords": [
    "jetpack"
  ],
  "preferences": [{
    "name": "openInTab",
    "title": "Open in Tab or Window?",
    "label": "Open in tab or window",
    "description": "Allows to open source code in a new tab (default) or a new window",
    "type": "radio",
    "options": [{
      "label": "Tab",
      "value": true
    }, {
      "label": "Window",
      "value": false
    }],
    "value": true
  }],
  "permissions": {
    "private-browsing": true,
    "multiprocess": true
  }
}

Set multiprocess permission to true; require Fx52+
Set multiprocess permission to true; require Fx52+
