No confusion here, just a problem with the CGminer installation for CPU use only, as in my case of no separate GPU card and no OpenGL. It seems that the present installation is mainly for GPU mining with the CPU mining just on option, provided CGminer found the OpenGL first, to enable it to install.
I know that OpenGL could be installed separately, but at this moment, a much simpler solution of disabling the need of detecting the OpenGL at CGminer installation for CPU mining only, looks much more elegant.