As reported by Erfane Arwani:
There is one more combination that does not work.
On MAC-FR keyboard under Mavericks (Firefox, Safari & Chrome), I can not obtain the "€" character.
Normally, to get the "€", I press the option key (alt) and * key.
Please find the ouput of http://guac-dev.org/pub/tests/guac/keyboard-test.html :