I you use XQuartz from MacPorts you need to change X11 to local

[mobluse]

It's not a real issue, but it might affect the documentation.

In OS X El Capitan 10.11.6 I installed XQuartz using sudo port install xorg-server and then I had to change X11 to local in the build examples for src/CMakeLists.txt:

link_directories(/opt/local/lib)
target_include_directories(xace PUBLIC /opt/local/include)

and tests/CMakeLists.txt:

link_directories(/opt/local/lib)
target_include_directories(keyboard_test PUBLIC /opt/local/include)
target_include_directories(spooler_test PUBLIC /opt/local/include)