[bl4ckcontact]

If I recall, F6 should get what you’re after.

[spurgu]

As I said I want it specifically to be Cmd+D (instead of the default Cmd+L).

[atwood22]

It would be pretty trivial to write an extension that does that.

[dan-robertson]

I don't think Firefox extensions can do this sort of thing.

[atwood22]

Yea you’re right. Looks like they removed the ability of extensions to do that back in 2017. Sad :(