Reference

XUngrabDeviceKey(3x) on Linux

The text bc6d40fa8fb3, as Debian 2.2 (Potato), Debian 2.1 (Slink), Debian 2.0 (Hamm), Debian 1.3 (Bo) shipped it.

grab/ungrab extension input device Keys

XUngrabDeviceKey(3x) on Linux now