Fade in and fade out folder indicators

[GoogleCodeExporter]

Describe the feature you want implemented.
Hover over the left pane in Explorer and the folder indicators fade in, move 
the mouse away from that area and the indicators fade away.

Describe why you think that this feature is needed.
This is one step closer to implementing features from Explorer that will make 
Stoffi even more beautiful and consistent with what users already know from 
using Explorer.

Are there any other projects that inspired you?
Windows Explorer

Do you have any screenshots or mockups to show a concept of this feature?
No need, just look at the black triangle to the left of the folder name in the 
left pane in Explorer.

Is there anything you can help us with in implementing this feature
(coding, testing, translating, designing, documenting, etc)?
QA

Can you please consider this for Zhou?

Original issue reported on code.google.com by [email protected] on 23 Apr 2012 at 11:48