menu: example for scrolled content (close #555)

close #555 
![2014-06-18_1007](https://cloud.githubusercontent.com/assets/521273/3310171/ea13ac0c-f6ae-11e3-94f5-7c048f69cce4.png)
![2014-06-18_1015](https://cloud.githubusercontent.com/assets/521273/3310228/00aa0348-f6b0-11e3-8c5b-0f6ccba81e9d.png)