On computers using macOS, idleness is based on actual user idleness, not just Emacs’ idle time. For X11, you can install a utility program ‘x11idle.c’, available in the ‘contrib/scripts/’ directory of the Org Git distribution, or install the xprintidle package and set it to the variable org-clock-x11idle-program-name if you are running Debian, to get the same general treatment of idleness. On other systems, idle time refers to Emacs idle time only.
(defcustom org-clock-watch-focus-emacs-window-command-str ""
"shell command string to focus emacs window, empty string means this function is off,
on linux you can use `wmctrl -xa Emacs', on windows you can reference `nircmd' or other command
"
:group 'org-clock-watch
:type 'string)
Emacs is able to send “notifications” on systems that support the
freedesktop.org Desktop Notifications Specification and on MS-Windows.
In order to use this functionality on POSIX hosts, Emacs must have been
compiled with D-Bus support, and the ‘notifications’ library must be
loaded. ....