Adds a button for copying text from the translation source inputbox in Google Translate

google-translate-copy-button.user.js

// ==UserScript==
// @name         Google Translate Copy Button
// @namespace    http://nkmathew.net/
// @version      0.1.0
// @description  Adds a button for copying text from the translation source inputbox in Google Translate
// @icon         http://translate.google.com/favicon.ico
// @icon64       http://translate.google.com/favicon.ico
// @author       nkmathew
// @match        https://translate.google.com/*
// @grant        none
// ==/UserScript==

(function() {
  'use strict';

  var copyButton = document.getElementById('gt-res-copy').cloneNode(true);
  var srcToolbar = document.getElementById('gt-src-tools-l');
  copyButton.classList.add('goog-toolbar-button-hover');
  copyButton.style.display = 'block';
  srcToolbar.appendChild(copyButton);

  document.querySelector('.copy-button').addEventListener('click', function(event) {
    document.getElementById('source').select();
    document.execCommand('copy');
  });

})();