loader.html

<script>
  var active = false;
  var new_win;
  // Load native UI library.
  var gui = require('nw.gui');

  // Get the current window
  var win = gui.Window.get();

  var option = {
    key : "Alt+Shift+A",
    active : function() {
      // New window options
      var new_win_option = {
        "title": "IAM",
        "toolbar": false,
        "frame": false,
        "always-on-top": true,
        "transparent": true,
        "no-edit-menu": true,
        "single-instance": true,
        "show": true,
        "node-remote": "*",
        "width": 800,
        "height": 500,
        "position": "center",
        "min_width": 400,
        "min_height": 200,
        "max_width": 800,
        "max_height": 600
      };

      if (new_win) {
        new_win.close();
        new_win = false;
      } else {
        new_win = gui.Window.open('/index.html', new_win_option);
        new_win.on('loaded', function () {
          // new_win.show();
          new_win.focus();
        });
      }

      // And listen to new window's blur event
      // new_win.on('blur', function() {
      //   new_win.close();
      // });

      // focused = !focused;
      // if (focused) {
      //   win.show();
      //   win.focus();
      // } else {
      //   win.blur();
      //   win.hide();
      // }
    },
    failed : function(msg) {
      console.log(msg);
    }
  };

  win.hide();
  win.blur();

  // Create a shortcut with |option|.
  var shortcut = new gui.Shortcut(option);

  // Register global desktop shortcut, which can work without focus.
  gui.App.registerGlobalHotKey(shortcut);

  // You can also add listener to shortcut's active and failed event.
  // shortcut.on('active', function() {
  //   win.show();
  //   win.focus();
  //   console.log("Global desktop keyboard shortcut: " + this.key + " active.");
  // });
  //
  // shortcut.on('failed', function(msg) {
  //   console.log(msg);
  // });

  win.blur();

  // Unregister the global desktop shortcut.
  // gui.App.unregisterGlobalHotKey(shortcut);
</script>