menu improvements

- [x] fix context menu with dark theme
- [x] improve menu / context menu style, the current is ugly

![image](https://f.cloud.github.com/assets/658431/1453297/9866a02c-42ee-11e3-8255-b1c8af5d92e4.png)
![image](https://f.cloud.github.com/assets/658431/1453298/9b35fece-42ee-11e3-92df-ae4bb215e28b.png)
![image](https://f.cloud.github.com/assets/658431/1453299/9d44c13c-42ee-11e3-945c-f88724d87195.png)
![image](https://f.cloud.github.com/assets/658431/1453300/9f1334bc-42ee-11e3-9332-bf7e084a7614.png)
![image](https://f.cloud.github.com/assets/658431/1453301/a0b001d8-42ee-11e3-8748-d70fc0118e55.png)


Closes #745 
Apart of #744