How to switch two -> single panel modes?

[Cade Foster <ahx2323 gmail com>]

Hello.
Does anyone know how to hide the second panel in one keyboard hot key?

Currently, we may do this by pressing <M-t> three times and manually set user_format (from "panels.ini") from
user_format=full name type size:4
to
user_format=half name type size:4
and vice versa.

Thanks.