This answer gave me the solution I needed. The only problem for me, is that I have to load it, namely fic-mode, manually. More explicitly, whenever I open a c++ file, I have to do M-x fic-mode and then M-x font-lock-fontify-buffer in order to have it really up and running. In my .emacs I have
(require 'fic-mode)
(add-hook 'c++-mode-hook '(lambda () (fic-mode 1)))
but it doesn't do the trick.
Do you have any suggestions how to make it available automatically?