Dropbutton

Implements:
![screen shot 2014-07-17 at 2 04 12 pm](https://cloud.githubusercontent.com/assets/2559233/3617273/cd5c6f46-0ddc-11e4-8742-43fe68fee342.png)

that expands as:

![screen shot 2014-07-17 at 2 04 17 pm](https://cloud.githubusercontent.com/assets/2559233/3617275/d266aac4-0ddc-11e4-89b8-a24d96783073.png)