bug#1077: 23.0.60; x-create-frame: (wrong-type-argument number-or-marker-p nil)

[Eli Zaretskii]

> Date: Tue, 30 Nov 2010 08:56:41 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: Drew Adams <drew.adams@oracle.com>, 1077@debbugs.gnu.org
> 
> `menu-bar-lines'
>       The number of lines to allocate at the top of the frame for a menu
>       bar.  The default is 1.  A value of `nil' means don't display a
>       menu bar.

Is it different from (menu-bar-lines . 0) ?  If not, do you happen to
know why are we using two different conventions to convey the same
information?