Set of two scripts to be run as root and display notifications to logged in users.
First script (root-notify-send) sends the message to all currently logged in users by iterating over processes of window managers. Accepts parameters which are passed to the notify-send.
Second script (root-notify-user) sends the message to a single user. The username is passed as the first parameter, the rest of them is passed to notify-send.
# root-notify-send "A"
x11-misc/root-notify-send Ebuild available in nitratesky overlay. The ebuild includes the option to replace notify-send with dunstify.