My laptop has a dedicated lock key, which sends a Super_L+L messing with unity and making it rather useless.
I have no idea how to fix this as I get 2 keycodes with
acpi_listen gives no output. Any ideas?
The key code conversion is likely happening within the ACPI BIOS routines, making the key press indistinguishable from a Win+L key sequence.
There is a similar issue with some laptops that generate a Win+P key sequence when you press their dedicated video output switch key, and there isn't much you can do about it.
Depending on how common this lock screen key stroke becomes, Unity may just have to adapt.