It would be nice to see the status (activated/deactivated) in the chat (client only).

If I'm underground in a completely mob proof room, I can't tell if the overlay is activated or not, even if I switch it via the hotkey.

That is a very needed feature! I also miss an easy way to know the status!

@AC-ID : you can see the current status using F3 (near the bottom). That's what I'm doing, but that's a cumbersome way to check status.

IMHO, Light Overplay could have two kinds of status messages:

• On F7, prints a timed message (similar to in-game "you can only sleep at night" or "cat drowned"), so we know if we are enabling or disabling it. I believe this is what the OP requested, and that's a feature I miss a lot. Please implement at least this one!
• A permanent message if it is disabled, like a single "Light Level is DISABLED" written in red on top of the screen, or a more subtle (but always visible) marker. This marker/message could be disabled in options.

The idea is: Light Overlay should always be ON, but in some conditions I turn it off (exploring overworld, hunting mobs, etc), and it's a huge risk to forget to turn it back on when back at base and explored mines, as there is no visual cue that it is OFF, we assume everything is safe when it might be not.