Fixed border drawing glitch

Border was drawn on half pixels on odd border width.

Before:
![before](https://f.cloud.github.com/assets/1267950/227912/cf8f90cc-866f-11e2-9ae7-129e8e1c0620.png)

After:
![after](https://f.cloud.github.com/assets/1267950/227913/d48ef040-866f-11e2-9c68-eb896c846f07.png)