Install libgconfmm-2.6-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libgconfmm-2.6-doc
Description:
C++ wrappers for GConf (documentation)
GConf is a system for storing application preferences. gconfmm is the C++ wrapper for GConf. . This package contains development reference documentation and examples.
Homepage: http://www.gtkmm.org/
Version: 2.28.3-1
Section: universe/doc