character composition seems much worse than before

[Miles Bader <miles.bader.fz@renesas.com>]

For a while, maybe 4-5 months ago (?), automatic composition
in Emacs seemed to be working really well -- things just
_worked_, and worked correctly in almost every case.

Now it seems to be a fair bit worse... E.g.:

I do (using emacs -Q, latest trunk):

 (1) Insert a letter "e" by typing it

 (2) Insert a unicode combinging accute accent by doing "C-x 8 RET"
     and then "COMBINING ACCUTE ACCENT" RET

*Previously* (meaning N months ago), that would then properly
display an accented "e" character, which looked exactly like
the precombined unicode "é".  Perfect!  One could even add
multiple combining accents and they all displayed correctly
stacked on top of each other.  It was impressive.

But now:

 + It doesn't work by default -- it seems that I need to do
   "M-x auto-composition-mode" first.  Why is this necessary?
   Aren't combining characters almost always intended to, well,
   combine?  Why would we want them to _not_ combine by
   default?

 + The accent positioning is fairly clearly wrong.  I know this
   is font-specific, but this is using "Bitstream Vera Sans
   Mono" which is a pretty standard free font, and with which
   the positioning seemed to be perfect before.

 + Some combining accents seem to simply not work at all.  If I
   insert an "e", and then a "COMBINING CIRCUMFLEX ACCENT"
   character, the latter simply displays as a separate
   character, not stacked on top of the "e".  This used to work
   properly (and is a legimate combination -- there's a
   precombined "LATIN SMALL LETTER E WITH CIRCUMFLEX"
   character.

 + Multiple combining accents seem to display very badly, not
   stacked properly, but instead seemingly all at the same
   location (resulting in an unreadable blob).  This also used
   to work "properly."

Maybe there's something wrong with my system or my font, but I
think it's a reasonably standard Debian distro, with a standard
font...

Do these things work for other people?

[Well, I guess the question of whether "auto-composition-mode"
is valid regardless.]

Thanks,

-Miles

-- 
Patience, n. A minor form of despair, disguised as a virtue.