Fixed transparent tabs in nautilus

Fixed transparent in nautilus when tabs opened. However, upon closing all tabs and left with one, the viewport all turns transparent in turn. see image
![screenshot from 2014-12-19 23 29 49](https://cloud.githubusercontent.com/assets/5289083/5512660/34ad96b0-87d7-11e4-8529-eee62b18aef1.png)