Hmmm, going through the new package list, this one looks interesting:
p xcape <none> 1.1-1
Configure modifier keys to act as other keys when pressed and released
xcape allows you to use a modifier key as another key when pressed and released
on its own. Note that it is slightly slower than pressing the original key,
because the pressed event does not occur until the key is released. The
default behaviour is to generate the Escape key when Left Control is pressed