bug#18818: Incorrect font weight in dark background, Emacs 24.4 on Mac OS X 10.10

[YAMAMOTO Mitsuharu]

>>>>> On Sat, 18 Jun 2016 15:45:23 +0100, Alan Third <alan@idiocy.org> said:

>> Screenshots after each step are attached.  It's clear that in a
>> dark background, bold and normal texts are flipped.

> I can confirm this in Emacs 25. It looks like it's only synthetic
> bolds that are displayed incorrectly, faces with proper bold fonts,
> like Menlo, are displayed correctly.

> Looks like the Mac port behaves identically.

This is a long-standing bug in Core Graphics.  The Mac port contains
an info node suggesting some workaround:

     Also, synthetic bold looks thinner if the background is darker than
  the foreground and the LCD font smoothing is turned on.  In such cases,
  you can turn off synthetic bold for particular fonts and use
  overstriking instead by customizing the variable ‘face-ignored-fonts’:

       (add-to-list 'face-ignored-fonts "\\`-[^-]*-monaco-bold-")

https://bitbucket.org/mituharu/emacs-mac/src/292d5368c1f209977c03ed6e1b2107aab37bfd92/doc/emacs/macport.texi?at=master&fileviewer=file-view-default#macport.texi-339

                                     YAMAMOTO Mitsuharu
                                mituharu@math.s.chiba-u.ac.jp