I've installed Ubuntu 17.10 on my Imac (mid 2011) next to mac OS Sierra, managing this dual boot with rEFind 0.11.2. I'm using the original keyboard and the Magic Mouse, connected using bluetooth. The problem is that when I configure them in mac OS, Linux doesn't recognize theme and I'm not able to log in and vice versa. Do you know how could I resolve that problem? I'm not so expert, even if I've used Ubuntu for a long time on a laptop (it was pretty simpler than today).
Thanks to everyone, I really appreciate your help. I'm sorry for possible mistakes but I'm not mother tongue.