I've checked it myself, and the BIOS is responsible to dim the brightness to 0 when AC is removed. This is very strange, but it's not ubuntu's fault. Thanks
** Changed in: gnome-power-manager (Ubuntu) Status: Incomplete => Invalid -- brightness decreased even if asked not to do https://bugs.launchpad.net/bugs/249439 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs