acme-sac: analysis osx :., idiom problem

(ok, analysis is probably wrong wording. anyway.)

I looked at the problems I had with :, and :., on acme-sac os-x.

one of the things that happens with single-click b3 actions is that
the selection is expanded, using character classes allowed for
file name part, regular expression, or address part.

to my surprise there is a difference in the list of characters
allowed by isaddrc (in regx.b) in inferno acme compared with
corresponding isaddrc in plan9/p9p acme (in addr.c).

p9p and plan9 allow:    0123456789+-/$.#,;
inferno/acme-sac allow: 0123456789+-/$.#

to me this explains why acme-sac refuses to match :,
but I don't understand why/how it does/could work on other platforms -
but I did not take the time to look at what happens there.

I added ,; to the list of characters allowed.
that makes the :, idiom work.

Furthermore there is some interesting interplay with the plumber that
on acme-sac osx  seems to match more than the plan9/p9p plumber do.
I saw that since the :, problem was mentioned already some changes
have been made to the acme-sac plumbing rules.

I took the latest acme-sac plumber rule file as base, and on :.,
I no longer get acme opening a new window showing non-existent
file /usr/axel/whatever/:.,
When I click to the right of the whole :., I get the correct behaviour;
when I click on :., with single click between : and .
then the expression get handed over to the plumber by acme sac,
and the plumber matches :., as directory, I guess,
so the cursor moves to the already open pane for that directory.
(did not try this without pane open for that directory)
mac osx weirdness?
could : be a separator in mac os x file names?

It seems the following acme-sac plumber rule matches for :.,  :

# existing directories go to acme
kind is text
data matches '[a-zA-Z¡-0-9_./\-]+'
data isdir	$0
data set	$dir
[etc]

I inserted a ^ in the pattern in the 'data matches', as in

data matches '^[a-zA-Z¡-0-9_./\-]+'

and then the :., idiom works as expected.
No idea what the insertion of ^ might break.

with these two changes (,; inserted in list of isaddrc chars,
and ^ inserted in pattern that match directories) things seem
to work for me. (find wood, knock 

Question not studied in detail:
why does current code work on the other platforms?

Axel.