Prevent deferral of code tab when nav-/toolbar item clicked

If an nav-/toolbar item is clicked, the code tab gets shifted to the right:

![auswahl_2017-09-06_01](https://user-images.githubusercontent.com/22935000/30099677-bc61f3b8-92e6-11e7-94b7-ad848c3becf3.png)

![auswahl_2017-09-06_02](https://user-images.githubusercontent.com/22935000/30099691-c52520ec-92e6-11e7-9515-a68c50033c3a.png)
