gistfile1.js

const widgets = require("widget");
const tabs = require("tabs");
var tabArray = [];

var widget = widgets.Widget({
  label: "Show tab history",
  id: 'tab history',
  contentURL: "http://www.mozilla.org/favicon.ico",
  onClick: function() {
    console.log('\n tab history:');
    let n = 0;
    tabArray.forEach(function(tab) {
      console.log('tab ' + n + ':');
      n++;
      tab.history.forEach(function(url) {
        console.log(url);
      });
    });
  }
});

tabs.on('open', function(tab) {
  tab.history = [];
  tabArray.push(tab);
});

tabs.on('ready', function(tab) {
// we need this special-case code
// because 'open' does not get generated
// for the first tab in the window
  if (!tab.history) {
    tab.history = [];
    tabArray.push(tab);
  }
  tab.history.push(tab.url);
});

tabs.on('close', function(tab) {
  var index = tabArray.indexOf(tab);
  if (index != -1) {
     tabArray.splice(index, 1);
  }
});