Arrow in sidebar

Hello!

I felt like the arrow in the sidebar was really missing so I found a way (through trial and error) to make it work. Please check my fork. 

Leszek

![screen shot 2013-05-19 at 19 29 29](https://f.cloud.github.com/assets/367876/522821/09ee9f68-c06f-11e2-8b9f-ad7ffe455764.png)