commandline-editor.js

    mappings.addUserMap(
      [modes.COMMAND_LINE],
      ['<C-i>'],
      'Edit commandline by external editor',
      function () {
        io.withTempFiles(
          function (file) {
            file.write(commandline.command);
            editor.editFileExternally(file.path);
            commandline.open(":", file.read(), modes.EX);
            return true;
          }
        );
      }
    );