Laptop hardware buttons don't work as expected.

[alanwalterthomas]

I resuscitated an old Toshiba Satellite P100 or P105 with xubuntu 17.10 32-bit. It mostly works, but the hardware buttons aren't properly configured.
The FN + Brightness Keys (F6, F7) cause a brightness indicator to appear and change, but the actual screen brightness does not change at all.
There is a media app key which does nothing. I'd like it to open vlc.
There is also a web browser key. If I press it, it opens a seemingly unlimited number of firefox instances as quickly as possible, which freezes the machine in less than a minute by consuming all RAM.
I'd like it to open just one instance.

How can I fix this?

Thanks!

[kerry_s]

settings-> keyboard-> shortcuts

[alanwalterthomas]

I looked at that. It doesn't help.
In XFCE Settings->Keyboard lets me choose from Behavior;Application Shortcuts;Layout tabs. Application shortcuts has a list. I can enter a command triggered by what's identified as XF86MonBrightnessDown, but what should that command be? xbacklight -set 0 has no effect.

[kerry_s]

find your monitor, mine is LVDS1

xrandr --listmonitors

try command, this is for 50%

xrandr --output LVDS1 --brightness 0.50

100%

xrandr --output LVDS1 --brightness 1.0

if those work we can move forward from there.