title: API Call 'tabs.captureVisibleTab' is not supported in Edge
body: <p>I'm using Edge on Windows 10 v1703, build 15063.296.
  The documentation (<a href="https://docs.microsoft.com/en-us/microsoft-edge/extensions/api-support/supported-apis" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/microsoft-edge/extensions/api-support/supported-apis</a>) states, that the API tabs.captureVisibleTab is available.</p>
  
  <p>But when I use it in the background script, I'm getting the following error:</p>
  
  <blockquote>
    <p>API Call 'tabs.captureVisibleTab' is not supported in Edge.</p>
  </blockquote>
  
  <p>The code is:</p>
  
  <pre><code>browser.tabs.captureVisibleTab(currentTab.windowId, {format: "png"}, function (data) {});
  </code></pre>
  
  <p>Am I missing something?</p>
  
  <h2>UPDATE:</h2>
  
  <p>this is my manifest file (ported from Chrome): </p>
  
  <pre><code>{
  "author": "Evgeny Suslikov",
  "background": {
      "page": "background.html",
      "persistent": true
  },
  "browser_action": {
      "default_icon": {
          "19": "images/sss_19.png"
      },
      "default_title": "FireShot - Capture page",
      "default_popup": "fsPopup.html"
  },
  "commands": {
      "last-used-action": {
          "suggested_key": {
              "default": "Ctrl+Shift+Y",
              "mac": "Command+Shift+Y"
          },
          "description": "__MSG_options_label_last_action_hotkey__"
      }
  },
  "default_locale": "en",
  "description": "__MSG_application_description__",
  "icons": {
      "16": "images/sss_16.png",
      "32": "images/sss_32.png",
      "48": "images/sss_48.png",
      "128": "images/sss_128.png"
  },
  "Key": "B5SSrXXpDZAoT8SQ4vAzNeTQ1tBC2Z24nx+hHZXfykmVYfMy5aOwPkf0Hbt7SXlKbprwV0GwrYgCwIDAQAB",
  "manifest_version": 2,
  "name": "__MSG_application_title__",
  "offline_enabled": true,
  "optional_permissions": [
      "tabs",
      "&lt;all_urls&gt;",
      "downloads"
  ],
  "options_page": "fsOptions.html",
  "permissions": [
      "activeTab",
      "tabs",
      "contextMenus",
      "nativeMessaging"
  ],
  "short_name": "FireShot",
  "version": "0.98.92",
  "web_accessible_resources": [
      "images/*.gif"
  ],
  "-ms-preload": {
      "backgroundScript": "backgroundScriptsAPIBridge.js",
      "contentScript": "contentScriptsAPIBridge.js"
  },
  
  "content_scripts": [{
      "matches": ["&lt;all_urls&gt;"],
      "js": ["scripts/fsUtils.js", "scripts/fsSelection.js", "scripts/fsLinks.js", "scripts/fsContent.js"]
  }]
  }
  </code></pre>
  
  <p>In my fsBackground.js page I do the call:</p>
  
  <pre><code>     browser.tabs.captureVisibleTab(windowId, {format: "png"}, function (data) {});
  </code></pre>
  
  <p>I get the following error: <a href="https://i.stack.imgur.com/iELcN.png" rel="nofollow noreferrer">click to see screenshot...</a></p>