More contrast in highlighted/selected message

Attached is a suggestion for some slight changes in calculating colors for the highlighted message. It could be made configurable as well, but currently the implementation doesn't allow that. Is this a bad idea? How does it work with your terminal color schemes?

![2013-09-30-114750_1364x634_scrot](https://f.cloud.github.com/assets/56827/1236065/ad343f4c-29b6-11e3-964a-a480476ee174.png)