The parameter /apps/metacity/general/focus_new_windows in gconf has two
parameters smart and strict that concern only a Xterminal but with poor effect
with others applications.
Imagine a slow application that you launch. You are working with an editor
or another application during the waiting of the slow application. When you
type a word, you could validate a dialog box that popups or other unwanted action.
You could imagine other bad effect.  The security is concerned.

KDE has a fuller mecanism for that. I require a similar mecanism or better.