Restore or unmaximize window with, say, four-finger swipe down gesture on touchpad

## Problem

Currently there is an option to swipe up with four fingers to maximise a window but there does not seem to be a corresponding option to swipe down with four fingers to restore (unmaximise) the window.

## Proposal

Add a setting and gesture to restore/unmaximise windows with downward (four finger?) swipe.

## Prior Art

(unknown)