Default fonts for menus, dialogues, etc

[Richard Stallman]

Emacs lets the user customize the colors used by menus by customizing
a special face.  When the user sets the "inverse video" flag in that
face, for Emacs to do the right thing it must be able to determine
what colors would be used by default.  It can check for resources to
specify them, but what if there are no resources--what colors would be
used then?

One suggestion was that Emacs should define fallback resources to
specify the foreground and background colors.  That does enable Emacs
to determine, always, what colors are to be used.  But is this proper
behavior for an application?  It could mean an inconsistency between
Emacs and other applications in regard to how they display menus.  Is
that a real issue?

Is there some rule that says what the default menu colors should be
when there are no resource to specify them?  Or is each toolkit
ideosyncratic in that regard?  Currently Emacs supports the Athena
widgets and LessTif/Motif.