Ok to set a face on `mode-name' for so-long-mode?

[Phil Sainty <psainty@orcon.net.nz>]

I'd quite like to make the following change to lisp/so-long.el:

  ;;;###autoload
-(define-derived-mode so-long-mode nil "So Long"
+(define-derived-mode so-long-mode nil
+  (propertize "So Long" 'face 'so-long-mode-line-active)
    "This major mode is the default `so-long-action' option.

(`so-long-mode-line-active' simply inherits from `mode-line-emphasis'
by default.)

It will make the face consistent with that applied to
`so-long-mode-line-label' (by `so-long-mode-line-info') when other
(non-major-mode) actions are active.

In testing the change seems fine.  Is there any reason not to do this?

I think I'd initially felt that I shouldn't be messing with the face
for the something as standard as the major mode name; but on account
of having made the `so-long-mode-line-active' face rather high-contrast
in my own config, it now seems like a flaw that `mode-name' isn't using
that face.

I note that the new mode-name for `emacs-lisp-mode' sets a face for
the dynamic-binding flag "/d" if that's active, so there's at least
one example of something similar.


-Phil