Export view area.

#123 


![export1](https://f.cloud.github.com/assets/99186/1829474/8d9cccdc-72c0-11e3-8dd5-9567f4b85369.png)
![export2](https://f.cloud.github.com/assets/99186/1829475/935942b8-72c0-11e3-9b1a-c051bcf9436e.png)