brightness control keys don't work after upgrade to 13.10

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I'm really not sure if 'kwin' is the source of the problem.

Status changed to 'Confirmed' because the bug affects multiple users.

I have AMD/ATI Mobility Radeon HD 5430. lshw says HD 5430/5450/5470. I removed the proprietary fglrx driver and it seems to work again:

How to do that:

# sudo apt-get remove --purge fglrx fglrx_* fglrx-amdcccle* fglrx-dev*

# sudo rm /etc/X11/xorg.conf

# sudo apt-get install --reinstall xserver-xorg-core xserver-xorg-video-intel libgl1-mesa-glx libgl1-mesa-dri libgl1-mesa-glx:i386 libgl1-mesa-dri:i386

# sudo dpkg-reconfigure xserver-xorg

Then reboot the computer.

Source: http://xpressrazor.wordpress.com/2013/05/31/fix-catalyst-driver-in-ubuntu-13-04/

So the problem is probably something in the video driver.