Today I was working in an application that needs extensive use of function keys and after a brief bit of annoyance, I was relieved to learn about the function lock feature (Fn + Esc toggles whether the function keys or media keys are the default for the top row). However, I find it slightly annoying that there’s no visible indication on the keyboard about which behavior is the current default.
I think it would be a great improvement if a future iteration of the keyboard had a single LED light on the Escape key (just like the one on Caps Lock) to quickly convey whether the function keys or media keys are currently the default.
If you’re feeling inclined to take on a challenge, someone has documented the process of adding a Fn lock light by modifying the embedded controller firmware: