Edit: More Info
Under --->Menu --->System Tools I found Configuration Editor.
Under the tab "apps" I found the "gnome-power-manager"
Changing the check marks there has no impact. I can not adjust the brightness and/or
hibernate/shutdown time if running idle. After closing the lid the cooling fan keeps
running and drains the battery really fast.
What is to do to shut-down if idle for more than x minutes?