Rating control feedback when using mouse

[tallichet]

When you use mouse to change the rating value, decreasing it, old stars keep colored while the mouse is over.

To reproduce:

1. create a Rating control of 5 stars.
2. With a mouse, set it to 4.
3. Mouse mouse ouside of the control
4. with a mouse, set it to 2.
5. before moving the mouse outside, notify the 3th and 4th stars still have the same color.