bug#72986: Disabling menu-bar-mode changes size of new frames

[martin rudalics via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

 > I checked out git master HEAD (currently df57e44a08f) and reverted commit
 > 241616831024c9c9fe2b2378b611db0a560b9675 on top of that.

Good.

 > and please first run without the commit under
 >> gdb with a breakpoint at the line
 >>
 >>         adjust_frame_size (f, -1, -1, 2, 0, Qmenu_bar_lines);
 >>
 >> in xg_update_frame_menubar.  Please note all values you see after doing
 >>
 >> p req.height
 >>
 >
 > 50 (before initial frame opens)
 > 50 (after C-x 5 2, before second frame opens)
 >
 > And the second frame opens at the expected size, the same size as the first.
 >
 > Then restore current master and repeat the same steps.  When the values
 >> differ, this should tell us something about what happens.
 >>
 >
 > 50 (before initial frame opens)
 > 50 (after C-x 5 2, before second frame opens)
 >
 > But the second frame opens small.

Inexplicable to me.  Please conduct both runs once more.  But rather
than using the debugger simply evaluate

(setq frame-size-history '(100))

in the initial frame, do C-x 5 2, evaluate

(frame--size-history)

and post the contents of the the buffer *frame-size-history* for each
run here.  Maybe we can see some difference then.

martin