zathura: set default window-icon

pkgs/applications/misc/zathura/core/default.nix

···
-{ stdenv, fetchurl, pkgconfig, gtk, girara, gettext, docutils, file, makeWrapper }:
+{ stdenv, fetchurl, pkgconfig, gtk, girara, gettext, docutils, file, makeWrapper, zathura_icon }:
 
 stdenv.mkDerivation rec {
   version = "0.2.7";
···
   makeFlags = [ "PREFIX=$(out)" "RSTTOMAN=${docutils}/bin/rst2man.py" "VERBOSE=1" ];
 
   postInstall = ''
-    wrapProgram "$out/bin/zathura" --prefix PATH ":" "${file}/bin"
+    wrapProgram "$out/bin/zathura" \
+      --prefix PATH ":" "${file}/bin" \
+      --prefix XDG_CONFIG_DIRS ":" "$out/etc"
+
+    mkdir -pv $out/etc
+    echo "set window-icon ${zathura_icon}" > $out/etc/zathurarc
   '';
 
   meta = {

pkgs/applications/misc/zathura/default.nix

···
 rec {
   inherit (pkgs) stdenv;
 
+  icon = ./icon.xpm;
+
   zathura_core = callPackage ./core {
     gtk = pkgs.gtk3;
+    zathura_icon = icon;
   };
 
   zathura_pdf_poppler = callPackage ./pdf-poppler { };
···
 
   zathuraWrapper = stdenv.mkDerivation {
 
-    inherit zathura_core;
+    inherit zathura_core icon;
 
     name = "zathura-${zathura_core.version}";
 
···
       zathura_djvu
       zathura_ps
     ];
-
-    icon = ./icon.xpm;
 
     builder = ./builder.sh;