amd64 8.0: mutable visuals don't work?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

I've run into another issue with the commercial turnkey I've mentioned
here already that I'm trying to move to NetBSD 8.0.

This time, the problem is that, it appears, mutable visuals simply
don't work.  I have a tiny little program that looks for a depth-8
PseudoColor visual, allocates a colourmap, allocates a cell in the
colourmap, installs that colourmap, and puts up a window with that
visual, colourmap, and background pixel.  Then, based on input read
from stdin, it sets the colourmap cell to one of the 8 primary colours
(black, red, green, blue, cyan, magenta, yellow, white, as identified
on stdin with the letters k, r, g, b, c, m, y, w).  This works fine
under 5.2 (provided, of course, there's no window manager running for
it to fight with over colourmap installation - this, like the target
application I'm working on, runs standalone - and the server is run
-depth 8, so there _is_ a depth-8 PseudoColor visual).  But under 8.0,
it doesn't work.  I'm starting X with

/usr/X11R7/bin/xinit /usr/X11R7/bin/xterm -geometry 80x24+0+0 -- /usr/X11R7/bin/X -once -retro -tst -depth 8

with, appended, one of -cc 0 through -cc 5 (specifying StaticGray
through DirectColor).  With static visuals, StaticGray, StaticColor,
and TrueColor, the xterm and the root weave look normal.  With
GrayScale and PseudoColor, I get, visually speaking, a black screen
with the X default cursor.  (I assume the xterm is there but just not
visible.)  With DirectColor, curiously, I get a very dim grey root
weave and the xterm window is black body and dim grey border.

In the cases where I can see the root weave and xterm, running my
program gives me a black window that stays black no matter what colour
I tell it to change to.  In the cases where the screen is all black, I
can't tell whether the window is there, but everything stays solid
black no matter what colour I tell it to change to.

I find it hard to believe that other visuals (a) don't work and (b) are
being advertised nevertheless, so I assume I'm doing something wrong.
But, especially in view of a simple xterm not working, I can't seem to
figure out what - I'm wondering if anyone might be able-and-willing to
help me.

The test program is only 160 lines long.  I've got it up for ftp from
ftp.rodents-montreal.org in /mouse/misc/nb8.0/X11/x-test.c for anyone
who cares to try it.

					Mouse