Install gnustep-back0.26-xlib by entering the following commands in the terminal:
sudo apt update sudo apt install gnustep-back0.26-xlib
Description:
GNUstep GUI Backend (xlib)
It is a backend component for the GNUstep GUI Library. The implementation of the GNUstep GUI Library is designed in two parts. The first part is the front-end component which is independent of platform and display system. This front-end is combined with a back-end component which handles all of the display system dependent such as specific calls to the X Window System. . This package provides the deprecated xlib backend.
Homepage: http://gnustep.org
Version: 0.26.2-3
Section: universe/gnustep