Now scrollbar only appears when mouse enters search view.

With new implementation, scrollbar in search view will only be visible when mouse enters it.
[Mouse not in search view]
![image](https://f.cloud.github.com/assets/4847382/1443349/5275dc5c-41e2-11e3-8144-67dd07782375.png)
[Mouse in search view]
![image](https://f.cloud.github.com/assets/4847382/1443350/6bf0a91e-41e2-11e3-8b01-2a2123106dec.png)