emacs menu font in GTK-2 and GTK-3

[Nelson H. F. Beebe]

I recently upgraded my desktop workstation, doubling my screen
resolution to 3840x2160 pixels, and changing from Solaris SPARC to
CentOS 7 x86-64.  The higher resolution has been welcome, but I'm
still struggling with selecting larger font sizes in several
applications, including emacs.

When emacs is linked with a GTK-2 library, such as
/usr/lib64/libgtk-x11-2.0.so.0 on CentOS 6, then a startup file of the
form

        % cat ~/.emacs.d/gtkrc
        style "menufont"
        {
            font_name = "URWPalladio          16"
        }

        widget "*emacs-menuitem*" style "menufont"

suffices to enlarge the menu bar

        File  Edit  Options  Buffers  Tools  Emacs-Lisp  Help

to a readable size.  

However, on CentOS 7, linking is to /lib64/libgtk-3.so.0.  The above
setting then has no effect, and the default menu font is too small to
be read comfortably.

A system call trace of emacs startup shows that with GTK-3, the file
~/.emacs.d/gtkrc is not even read; instead, the file
~/.config/pango/pangorc seems to be the only user-specific GTK startup
file that is read.  However, its syntax is different from that of
gtkrc, so it does not seem to be the place where emacs menu font
choices are made.

Does anyone on this list know how menu-bar font names and sizes are
chosen with GTK-3 is linked into emacs?

Once we figure this out, the doc/emacs/xresources.texi needs to be
updated to document the procedure for GTK-3 library support.

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- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
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