Proposed restyling of vertical dropdown scroll bar

Use a transparent white scrollbar. Also remove auto fading.

Before:
![before](https://cloud.githubusercontent.com/assets/40213/3298369/c23a1292-f600-11e3-9f58-5b927c894a69.png)

After:
![after](https://cloud.githubusercontent.com/assets/40213/3298368/c236e6b2-f600-11e3-820b-e7d1efb4dcea.png)