This is with my setup, admittedly. But it is a regression introduced
by vanilla Emacs: simply changing to this build from a build from a
week earlier (2014-01-23).
The effect: Now my *Completions* buffer is completely illegible
because it is transparent/weak/faded. I even use a special-display
frame for *Completions*, for which I define the background as
"LavenderBlush2". Nevertheless, the frame is transparent.
Everything about it is transparent: background, foreground, title bar,
everything. This effect makes *Completions* completely useless and
unusable.
I tried to take a screenshot to show you what I see, but the
*Completions* frame does not even show up at all for the screenshot
software. I.e., even though I can (barely) make out by eye that there
is a *Completions* frame there, when I create a screenshot covering
that area it does not show up at all in the screenshot.
I cannot use this build at all, unfortunately.
(I thought we were in a feature freeze.)