Writing Menu Apps

Everything at the right of the menu bar is a menu app: Wi-Fi, Bluetooth, the volume, the battery and the clock. A menu app is any program that prints a line, and a shell script is enough. Add yours to [Menu Apps] in ~/.config/gemwm/menu (see the menu bar).

How it talks

A menu app runs as long as the bar does, and talks over its stdin and stdout:

• Each line it prints replaces its item: text, icon<TAB>text, or icon<TAB>text<TAB>inverse for white text on black (as the battery shows when it’s low). An empty line hides the item.
• A fourth field is a tooltip, shown under the item while the pointer rests on it: icon<TAB>text<TAB>flags<TAB>tooltip, where flags is inverse or empty.
• The icon is a PNG file, or an inline 1-bit picture, bitmap:WxH:hex: each row in hex, eight pixels to a byte, the first pixel in the top bit and 1 for black. Either way it’s drawn 1:1, as it would be on the ST.
• A click on the item sends it click 1 (2 middle, 3 right), and each notch of the scroll wheel over it scroll up or scroll down.
• When its stdin closes, the bar has gone, and it should exit.

If an app exits after running at least 10 seconds, it’s restarted; one that dies right away is left alone (look in the session log, ~/.local/state/gemwm.log).

An example

The load average, every 5 seconds; a click opens htop:

#!/bin/sh
while :; do cut -d' ' -f1 /proc/loadavg; sleep 5; done &
ticker=$!
while read -r click; do setsid foot -e htop & done
kill $ticker

Then, in ~/.config/gemwm/menu, keeping the ones you want:

[Menu Apps]
Load = exec ~/bin/load-menu-app
Wi-Fi = exec gemwm-wifi --menu-app
Volume = exec gemwm-volume --menu-app
Battery = exec gemwm-battery
Clock = exec gemwm-clock

and restart the bar: pkill gemwm-menu; setsid gemwm-menu &.