Feature/4503/context switcher 2

Second (and better) attempt for http://applis-bretagne.fr/redmine/issues/4503

![Capture du 2013-01-07 14:37:01](https://f.cloud.github.com/assets/265319/47393/5d7189b4-58cf-11e2-9f5b-8bf406dcea8b.png)