Install afterstep-data by entering the following commands in the terminal:
sudo apt update sudo apt install afterstep-data
data files for AfterStep window manager
AfterStep is a window manager based on FVWM which attempts to emulate the NEXTSTEP look and feel, while retaining the configurability of its predecessor. Note that this window manager makes extensive use of the color palette. If you have only an 8-bit color display, it will run as packaged, but you may want to modify the configuration to use fewer colors. . The package contains data and configuration files needed by AfterStep.