Helping programs find their icons

[Mark H Weaver]

Hello Guix,

I've investigated why wicd-gtk is unable to find its icons and fixed it.
Looking at the output of strace, I found that when wicd-gtk looks for
icons, it searches for 'index.theme' files in many different directories
of the form:

  /gnu/store/.../share/icons/hicolor/

The icons it wanted were in one of the directories it searched, but
apparently the lack of 'index.theme' inhibited it from loading the fonts
from that directory.

I've found only one package that includes
share/icons/hicolor/index.theme, and that's 'hicolor-icon-theme'.  The
'index.theme' file turned out to be quite generic.  It describes the
directory structure, but does not list the individual icons present.

I modified the 'wicd' package to copy 'index.theme' from
'hicolor-icon-theme' into the same directory of 'wicd', and that fixed
the problem: wicd-gtk now has working icons.

However, this problem is quite widespread.  Many of our gtk packages
install icons into $out/share/icons/hicolor but have no 'index.theme',
and I suspect that's the reason the xfce application menu is missing so
many icons.

  inkscape-0.91
  emacs-24.4
  gtk+-3.14.7
  xfce4-session-4.10.0
  xfwm4-4.10.0
  exo-0.8.0
  thunar-1.4.0
  xfce4-panel-4.10.0
  xfdesktop-4.10.0
  xfce4-battery-plugin-1.0.5
  transmission-2.84

I think it might be helpful to add a post-install phase to
'glib-or-gtk-build-system' that installs 'index.theme' from
'hicolor-icon-theme' if $out/share/icons/hicolor exists.

We might also have to install 'index.theme' from 'gnome-icon-theme' if
$out/share/icons/gnome exists.

That is, unless someone has a better suggestion.  Any ideas?

    Thanks,
      Mark