Using Spacebar as $mod for i3 and others

• When space is pressed on its own then a space is typed (thanks to xcape.)
• When space is held with another key it will be chorded as a modifier for the WM.

Create an ~/.Xmodmap:

clear mod3
clear mod4
add mod3 = Hyper_L
add mod4 = Super_L Super_R

Add to your ~/.profile equivalent:

xmodmap /home//.Xmodmap
spare_modifier="Hyper_L"
xmodmap -e "keycode 65 = $spare_modifier"
xmodmap -e "add Hyper_L = $spare_modifier"
xmodmap -e "keycode any = space"
xcape -e "$spare_modifier=space"

Set in your i3 config:

set $mod mod3