Layer visualisation cleanup can obscure lines.

This is automatically formatted:
![image](https://cloud.githubusercontent.com/assets/7721540/18416181/e144a9dc-780c-11e6-9a98-78a700719743.png)

While lines are running behind other lines:
![image](https://cloud.githubusercontent.com/assets/7721540/18416183/e7cc156a-780c-11e6-90d4-fc5a1edd65ad.png)
