Version:           unspecified (using KDE 4.6.2) 
OS:                Linux

-brightness setting used to work out of the box in Lucid (KDE 4.4.2)
-it stopped working in Maverick (KDE 4.5.2)
-it still does not work in Natty (KDE 4.6.2)
-neither slider in battery monitor (system tray), nor hotkeys (Fn+F1/F2) work 

First reported here:
https://bugs.launchpad.net/ubuntu/+source/kdebase-workspace/+bug/775624
https://bugs.launchpad.net/ubuntu/+source/guidance-power-manager/+bug/791458

It does not depend on the kernel, as I can still set/get brightness
from the command line:

# echo 21 > /sys/class/backlight/panasonic/brightness

Thanks a lot for your help

Reproducible: Always

Steps to Reproduce:
-Left click on battery icon in systray
-Move brightness slider

Actual Results:  
-The slider is initially at 0 (leftmost position)
-Screen brightness does not change

Expected Results:  
-The slider's initial position should correspond to current brightness
-Brightness should change when moving the slider

I am not sure what package relates to guidance-power-management
I'll be happy to provide more specific information (please ask)
For the moment I add the following:

$ lsb_release -rd
 Description: Ubuntu 11.04
 Release: 11.04

$ dpkg -l |grep kde #cutting irrelevant parts
ii  kcm-gtk                               0.5.3-0ubuntu6                             Transitional package for kde-config-gtk
ii  kcm-touchpad                          0.5.3-0ubuntu1                             transitional package for kde-config-touchpad
ii  kde-config-gtk                        0.5.3-0ubuntu6                             Configuration module for GTK+ appearance in KDE
ii  kde-config-touchpad                   0.5.3-0ubuntu1                             touchpad configuration tool (synaptiks)
ii  kde-window-manager                    4:4.6.2a-0ubuntu5.1                        the K window manager (KWin)
ii  kde-zeroconf                          4:4.6.2-0ubuntu3                           zeroconf plugins and kio slaves for KDE
ii  kdebase-bin                           4:4.6.2-0ubuntu1                           core binaries for the KDE base applications
ii  kdebase-data                          4:4.6.2-0ubuntu1                           shared data files for the KDE base applications
ii  kdebase-runtime                       4:4.6.2-0ubuntu1                           runtime components from the official KDE release
ii  kdebase-runtime-data                  4:4.6.2-0ubuntu1                           shared data files for the KDE base runtime module
ii  kdebase-workspace                     4:4.6.2a-0ubuntu5.1                        KDE Plasma Workspace components
ii  kdebase-workspace-bin                 4:4.6.2a-0ubuntu5.1                        core binaries for the KDE Plasma Workspace
ii  kdebase-workspace-data                4:4.6.2a-0ubuntu5.1                        shared data files for the KDE Plasma Workspace
ii  kdebase-workspace-kgreet-plugins      4:4.6.2a-0ubuntu5.1                        KDE greet libraries for authentication
ii  kdegraphics-libs-data                 4:4.6.2-0ubuntu1                           data files for libraries from the kdegraphics module
ii  kdegraphics-strigi-plugins            4:4.6.2-0ubuntu1                           graphics file format plugins for Strigi Desktop Search
ii  kdelibs-bin                           4:4.6.2-0ubuntu4                           core executables for KDE Applications
rc  kdelibs-data                          4:3.5.10.dfsg.1-3ubuntu2.10.10.1           core shared data for all KDE applications
rc  kdelibs4c2a                           4:3.5.10.dfsg.1-3ubuntu2.10.10.1           core libraries and binaries for all KDE applications
ii  kdelibs5                              4:4.6.2-0ubuntu4                           transitional package for the KDE Development Platform libraries
ii  kdelibs5-data                         4:4.6.2-0ubuntu4                           core shared data for all KDE Applications
ii  kdelibs5-plugins                      4:4.6.2-0ubuntu4                           core plugins for KDE Applications
ii  kdemultimedia-kio-plugins             4:4.6.2-0ubuntu2                           transparent audio CD access for applications using the KDE Platform
ii  libdebconf-kde0                       0.1+git20101228-0ubuntu1                   Debconf KDE GUI library
ii  libkde3support4                       4:4.6.2-0ubuntu4                           the KDE 3 Support Library for the KDE 4 Platform
ii  libkdecore5                           4:4.6.2-0ubuntu4                           the KDE Platform Core Library
ii  libkworkspace4                        4:4.6.2a-0ubuntu5.1                        library for the kdebase workspace
ii  polkit-kde-1                          0.99.0-0ubuntu3                            KDE dialogs for PolicyKit


Hardware: Panasonic CF-T5 (I'm not sure if brightness control is supposed to work for desktops as well: if so I can report the same problem on two different desktop PCs)

$ sudo lspci -vv #relevant parts:

00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03) (prog-if 00 [VGA controller])
        Subsystem: Matsushita Electric Industrial Co., Ltd. Device 8338
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Interrupt: pin A routed to IRQ 16
        Region 0: Memory at d0200000 (32-bit, non-prefetchable) [size=512K]
        Region 1: I/O ports at 1800 [size=8]
        Region 2: Memory at c0000000 (32-bit, prefetchable) [size=256M]
        Region 3: Memory at d0300000 (32-bit, non-prefetchable) [size=256K]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [90] MSI: Enable- Count=1/1 Maskable- 64bit-
                Address: 00000000  Data: 0000
        Capabilities: [d0] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
        Kernel driver in use: i915
        Kernel modules: intelfb, i915

00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)
        Subsystem: Matsushita Electric Industrial Co., Ltd. Device 8338
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Region 0: Memory at d0280000 (32-bit, non-prefetchable) [size=512K]
        Capabilities: [d0] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-