Highlight save states in use

Save states which are in use will be highlighted. The colour that I chose isn't the greatest. I hope someone can find a more suitable colour (IMHO, the current colour is too... bright). 

![screenshot_2013-10-08-19-09-30](https://f.cloud.github.com/assets/1694861/1289318/7abf7f62-301f-11e3-91a9-159cbdbb34ed.png)

The currently selected item colour (blue) overrides the highlight colour.