Install libhud-gtk1-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libhud-gtk1-doc
Description:
GTK helpers for exporting items to the Unity HUD
Allows applications to add items into the HUD without requiring a menubar or other parsed GUI elements using standard GTK features. . This package contains developer documentation.
Homepage: http://launchpad.net/hud
Version: 14.10+17.10.20170619-0ubuntu2
Section: universe/doc