I'm using iterm2 together with tmux and I need the function keys. Ever since I got the TouchBar Macbook Pro and upgraded to HighSierra, the F4 key became disfunctional in iTerm2 and emacs.
- The F4 key is used to cycle through the open tabs in tmux forwards
- The F3 key (cycle backwards) and in fact all other F keys work as expected
- The F4 key worked before the HighSierra / Touchbar upgrade. I used Time Machine to migrate, so no configuration changed.
- The F4 also does not work with on an external Magic Keyboard, indicating a software / mapping issue.
I suspect that some change in High Sierra makes macOS not pass the F4 key on to applications, but I'm not sure. I have checked that no system wide keyboard shortcut is assigned to F4. What else could I check?
Update: The issue can be confirmed with the keyboard viewer, a program that allows to display all keys pressed. It clearly confirms that all keys except F4 are registered by the system while F4 is not.