navigation for pages: how to hide sub-pages

Hi all,

this must have been resolved before but I can’t find the right information in the mass of information:

How can I hide sub pages when their branch in the navigation is not selected?
I found the navigo plugin but it does not seem to work with WP 2.6 and I always prefer to solve such basics issues with built-in features.

Is it possible to reach the desired behaviour with wordpress out-of-the-box? If not, which plugins does it?

Thanks for your support,

Henning