bug#33682: 27.0.50; enriched-mode cannot save anonymous faces

[Eli Zaretskii]

> Date: Sun, 09 Dec 2018 11:27:15 +0100
> From: charles@aurox.ch (Charles A. Roelli)
> 
> C-x C-f /tmp/test-file
> M-x enriched-mode RET
> M-: (insert (propertize "foo" 'face '(:background "red"))) RET
> C-x C-s
> 
> Error: Invalid face: :background

Thanks.

When setting colors and other properties in Enriched mode, you are
supposed to use commands from facemenu.el (and/or the menu-bar menu
items it produces, under Edit->Text Properties).

The immediate reason for the error is that you should do this instead:

  M-: (insert (propertize "foo" 'face '((:background "red")))) RET

but I'm not sure we want to extend enriched.el to support arbitrary
face specs.  What is the real-life use case for that?