bug#17344: 24.3.90; REGRESSION: tooltip semi-transparent in *Completions*

[Drew Adams <drew.adams@oracle.com>]

I think this is the same bug as #16619, which we closed because it
seemed fixed.  However, I never checked the appearance of tooltip
frames in *Completions*, since I normally do not use tooltips.

The behavior I notice now concerns only tooltip frames - specifically
tooltips shown on completion candidates in buffer *Completions*: those
tooltips are semi-transparent.  I do not see the problem with tooltips
elsewhere.

Please see bug #16619 for background and context.  This is with my
setup.  The regression started with Emacs 23.1 - there is no problem
with Emacs 22.

And just as for what was noticed during the bug #16619 thread, if I set
`frame-alpha-lower-limit' to 100 instead of the default value of 20 then
the problem disappears.

(Of course, I do not want to do that in general, and this is for code
that other users will use - I cannot expect them to tweak
`frame-alpha-lower-limit'.  IOW, that workaround might help you
understand the problem and possibly find a solution, but it is not,
itself, a solution.)

Note that in my setup, *Completions* is a separate frame, and its input
is redirected to my standalone minibuffer frame.  Dunno whether this is
pertinent, but it might help to know it.

Please see bug thread #16619, which apparently isolates the commit that
introduced that regression.  (I'm guessing that that regression has been
only partly fixed and this report is about the same problem.)



In GNU Emacs 24.3.90.1 (i686-pc-mingw32)
 of 2014-04-12 on LEG570
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking 'CFLAGS=-O0 -g3' CPPFLAGS=-DGLYPH_DEBUG=1'