Hi Andreas. Many thanks for your answer. However, it's not exactly what I'm looking for (or what I've lost ;)). What you have in your screenshots are a minimized/closed navigation window and the "working" window with the welcome window on t he right.
I have just one window, with the navigation in a tab, and a welcome in a tab, and all other item opening in the same window as new tabs instead of new tabs in the window where the welcome tab is (hope that wasn't too confuse). Cheers, A