text: $('body').appendChild($.create('div', {
      id: '_dictionary'
  }));
  var selection = window.getSelection(),
      dialog = $('#_dictionary'),
      content;
  
  dialog.addEventListener('click', function(e) {
      e.stopPropagation();
      return false;
  });
  
  document.onkeyup = function(event) {
      if (event.code !== 'ControlLeft' && event.code !== 'ControlRight') {
          return true;
      }
      chrome.extension.sendMessage({
          type: 'iciba',
          word: selection.toString().trim()
      }, iciba);
  };
  
  function iciba(response) {
      content = `<p>英[${response.content.ph_en}] `;
      if (response.content.ph_en_mp3) {
          content += `<span class="_icon" data-audio="${response.content.ph_en_mp3}"></span>`;
      }
      content += `美[${response.content.ph_am}] `;
      if (response.content.ph_am_mp3) {
          content += `<span class="_icon" data-audio="${response.content.ph_am_mp3}"></span></p>`;
      } else {
          content += '</p>'
      }
      content += response.content.word_mean.join('<br/>');
      dialog.innerHTML = content;
  
      $$('span._icon')._.events({'click': function(e) {
          chrome.extension.sendMessage({
              type: 'playsound',
              audioSrc: e.currentTarget.dataset.audio
          });
          return false;
      }});
      document.addEventListener('click', hideDialog);
      dialog._.style({
          display: 'block'
      });
  }
  
  function hideDialog(event) {
      dialog._.style({
          display: 'none'
      });
      document.removeEventListener('click', hideDialog);
  }
  