Monspace font as squares

[Friedrich W. H. Kossebau]

Am Freitag, 2. November 2018, 20:23:13 CET schrieb Friedrich W. H. Kossebau:
> Am Freitag, 2. November 2018, 19:46:17 CET schrieb Antoine Hoarau:
> > I'm using AppImage yes.
> > In the Appimage Kdev5, if I change the font to anything else it works
> > fine,
> > except the build windows that seems stick with monospace.
> > Is there any way to change the build windows font ?
> 
> No, the font in the build windows is currently hardcoded to use the system's
> fixed font (QFontDatabase::systemFont(QFontDatabase::FixedFont), which is
> queried from the platform thene integration plugin.
> Which might be something based on QGenericUnixTheme, which sets a QFont
> initialized with the family "monospace" (&
> setStyleHint(QFont::TypeWriter);).
> 
> See
> https://code.woboq.org/qt5/qtbase/src/platformsupport/themes/genericunix/
> qgenericunixthemes.cpp.html
> 
> Not sure if that theme is really in use, but it might be. Also unsure how
> the resolution then happens, if that string is passed 1:1 to fontconfig.
> 
> Can you tell what the result of "fc-match monospace" is on the normal
> commandline and what in the embedded shell/konsole of KDevelop?

Another possible reason found meanwhile is that possibly the libfontconfig 
(2.8 as from centos 6) as used for the appimage and linked by the qt qpa 
plugin used in the appimage is not able to read some newer format of the font 
config files as supported by fontconfig >= 2.11 (as used on ubuntu 16.04).

A possible solution might be not to use the stock libfontconfig from centos 6 
for the appimage build, but also provide sources from a recent version of 
libfonrconfig which also supports reading the old config format, so both old 
and the new non-backward compatible font config file formats are supported.
Cmp. e.g. https://github.com/OpenShot/openshot-qt/issues/1775

Superficially researched by reading other bug reports on a quick web search, 
just dumping here to sync with what was said on irc.

Cheers
Friedrich