Okay, I give up: why is that--now that I've changed my default font to be
a CachedTTCFont rendering Arial from an MS Windows TTF--that various
"announcers" (e.g., the text appearing near the cursor when filing in a
changeset, loading a package from SqueakMap, filing in a TTCFont, etc.)
all render there text as white on white background (or transparent on
white background, I can't tell).  Except for this disappearing text bit,
I'm quite pleased with this contribution towards a better looking Squeak!
:)

Oh, yeah, what am I running: a nearly-vanilla 3.4a on Debian Linux, with
limited customization other than a few packages loaded off of SqueakMap.

Thanks in advance for the insight!