Install libsx-dev by entering the following commands in the terminal:
sudo apt update sudo apt install libsx-dev
Description:
Development files (headers and static libraries) for libsx
Libsx (the Simple X library) is a library of code that sits on top of and to the side of the Athena widget set. Its purpose is to make writing X applications *much* easier. . This package contains header files, pkgconfig files and static libraries for libsx.
Homepage: http://www.dei.isep.ipp.pt/~andre/normas/libsx.htm
Version: 2.08-2
Section: universe/libdevel