RE: font-lock-maximum-decoration should be 2 by default?

["Drew Adams" <drew.adams@oracle.com>]

> >> > > Interesting. I am curious of reasons for that.
> >> > 
> >> > Performance.  You don't gain much by omitting some fontifications
> >> > nowadays.  The variable was introduced to get snappier redisplay;
> >> > since the need for that is no longer valid, the default 
> >> > was set to t.
> >> 
> >> Do you have any proof of that being _the_ reason it was 
> >> introduced: just for performance?
> >
> > No proof, just my faulty memory.
> 
> In this case, not faulty:
> 
> ! (defvar font-lock-maximum-decoration nil
...
> ! (defvar font-lock-maximum-decoration t
...
> 1996-08-11  Richard Stallman  <rms@psilocin.gnu.ai.mit.edu>
> 	* Version 19.33 released.
> 1997-09-15  Richard Stallman  <rms@psilocin.gnu.ai.mit.edu>
> 	* Version 20.1 released.
> 
> (I thought there was also a 19.34, but that might be my faulty memory,
> or maybe it was on a branch, so doesn't show up in the changelogs).

Uh, where do you see ANYTHING there that supports the claim that "the" reason
why the variable was _introduced_ in the first place was "to get snappier
display"?

What you show supports the fact that the default value was changed from nil to t
in 1997.  Nothing more, AFAICT.  The question is whether the variable and its
levels exist _only_ to provide "snappier redisplay" (by choosing a lower level).

The variable is intended to give users a choice of different amounts of
font-lock decoration.  A user can want more or less decoration for any number of
reasons.  In the old days performance was no doubt one of the possible reasons.

If performance were the only reason for this variable, then those who want to
remove the variable now might have an argument.  (And in that case it could even
have been removed in 1997.)

It is clear to me that there are users, today, who want less fontification in
some modes (I've heard from some of them).  This variable gives them a way to
get that.

Yes, a default of `t' hides this possibility from some users, no doubt.  And
yes, there are too few modes that actually provide different levels.

And yes, one could perhaps dream up a better approach than levels.  But while
waiting for the better approach (conjectured by Stefan long ago), this variable
has the merit of providing users some control over the amount of decoration.