laptop screen randomly dims in ubuntu

There is another place to set gnome power manager options:

Start Gconf-editor:
Alt-F2 > type gconf-editor> run

Select apps menu > gnome-power-manager
There are some options to try:
- dim-on-idle
- backlight menu > idle-...

Now, notebooks have very specific hardware that have specific issues. Some options in some computer still don't work 

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