[WIP] Another MetroNavigationWindow Attempt

This time, I really want to fix @zhouzhipeng's issue: #692. Implements #789.
Fixes #692 

### Screenshots
#### First working build
![nav](https://f.cloud.github.com/assets/251501/1547041/279784c4-4d93-11e3-9874-406096cc6cd2.PNG)
![nav2](https://f.cloud.github.com/assets/251501/1547891/4f129460-4db3-11e3-931f-5ce02c5c38ba.PNG)
![nav3](https://f.cloud.github.com/assets/251501/1550638/4ef8b898-4e07-11e3-8920-c8c8253de6d1.PNG)