I use a toshiba laptop that uses ACPI. In gnome there is no way to easy change the brightness of the display without going to root in a terminal. Also, I can't remove my pcmcia adapter without being root in a terminal window. Both of which the average user would want to do. I can do this simply by clicking icons on the WindowsXP taskbar.
Also, when my battery runs low, I get an event in gnome, telling me the time left. If I ignore this message, my machine just powers off, and does not shutdown or suspend.
I have an idea that would use DBUS and HAL, much in the way of Project Utopia suggests.
A DBUS enabled service called, say, PowerService (with root privs) that could execute the needed commands:
#echo "brightness: 3" > /sys/acpi/toshiba/lcd
Depending on the value of a config file.
PowerService could also supply (a modified) battstat with it's information about battery levels and whether it is on mains or battery.
An extra applet could be designed to control the brightness of the lcd display, and also an eject applet (only visible if pcmcia card inserted) that would allow me to eject in one click.
PowerService could load a policy when the cable is removed, say for instance to slow the processor and to dim the screen.
I have created an applet that lets me change the brightness for the time being, but the idea of lots of small services for each task, and multiple applets with system-specific options is non-ideal.
Has this been done before? Or is it worth discussion? I thought I would try you guys at f-d-l and then try the gnome people when I know more good ideas/case studies.