Install libgail-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libgail-doc
Description:
documentation files of the Gail library
Gail implements ATK interfaces for GTK+ widgets which are dynamically loadable at runtime by a GTK+ application. Once loaded, those parts of an application that use standard GTK+ widgets will have a basic level of accessibility, without the need to modify the application at all. . This package contains the documentation files for Gail.
Homepage: http://www.gtk.org/
Version: 2.24.32-1ubuntu1
Section: doc