slackbuilds/desktop/icewm/README

IceWM is a window manager for the X Window System.  The goal of IceWM 
is speed, simplicity, and not getting in the user's way.

Because icewm users are perhaps less likely to use components of
other desktop environments, the following could be considered a
recommendation for addition to /etc/sudoers (use visudo(8) to edit
it), which will allow all members of the "power" group to use icewm's
built-in methods for shutdown, reboot, and sleep.

Cmnd_Alias POWERMGMT = /sbin/halt, /sbin/reboot, \
                       /sbin/poweroff, /usr/sbin/pm-suspend
%power ALL=(ALL) NOPASSWD: POWERMGMT

Some users might wish to have a polkit authentication agent or
other things invoked at X startup - see /usr/share/icewm/startup for
suggestions.