Install libcaribou-gtk-module by entering the following commands in the terminal:
sudo apt update sudo apt install libcaribou-gtk-module
Description:
Configurable on screen keyboard with scanning mode (GTK+ 2.0 module)
An input assistive technology intended for switch and pointer users. . This package contains the GTK+ 2.0 module library.
Homepage: https://wiki.gnome.org/Projects/Caribou
Version: 0.4.21-5
Section: universe/libs