Hi,

 renderElement: function(){
    this._$filterButtons = this.$('.o_filter_button');
    this._$previews = this.$('.o_mail_systray_dropdown_items');
    this._filter = false;
    this._updateCounter();
    var mailBus = this.call('mail_service', 'getMailBus');
    mailBus.on('update_needaction', this, this._updateCounter);
    mailBus.on('new_channel', this, this._updateCounter);
    mailBus.on('update_thread_unread_counter', this, this._updateCounter);
    return this._super.apply(this, arguments);
},

  When i try to run this i got  "Cannot read property 'getMailBus' of undefined".

 is there any option for resolving this error.

 i also tried mailmanager.call('mail_service', 'getMailBus')