nixpkgs/pkgs/development/libraries/qt-5/5.9/qtbase/qgtk-env.patch

Index: qtbase-opensource-src-5.8.0/src/plugins/platformthemes/gtk3/main.cpp
===================================================================
--- qtbase-opensource-src-5.8.0.orig/src/plugins/platformthemes/gtk3/main.cpp
+++ qtbase-opensource-src-5.8.0/src/plugins/platformthemes/gtk3/main.cpp
@@ -39,6 +39,7 @@
 
 #include <qpa/qplatformthemeplugin.h>
 #include "qgtk3theme.h"
+#include <QFile>
 
 QT_BEGIN_NAMESPACE
 
@@ -54,8 +55,22 @@ public:
 QPlatformTheme *QGtk3ThemePlugin::create(const QString &key, const QStringList &params)
 {
     Q_UNUSED(params);
-    if (!key.compare(QLatin1String(QGtk3Theme::name), Qt::CaseInsensitive))
+    if (!key.compare(QLatin1String(QGtk3Theme::name), Qt::CaseInsensitive)) {
+
+#ifdef NIXPKGS_QGTK3_XDG_DATA_DIRS
+        QStringList XDG_DATA_DIRS = QFile::decodeName(qgetenv("XDG_DATA_DIRS")).split(':');
+        XDG_DATA_DIRS << QLatin1String(NIXPKGS_QGTK3_XDG_DATA_DIRS);
+        qputenv("XDG_DATA_DIRS", QFile::encodeName(XDG_DATA_DIRS.join(':')));
+#endif
+
+#ifdef NIXPKGS_QGTK3_GIO_EXTRA_MODULES
+        QStringList GIO_EXTRA_MODULES = QFile::decodeName(qgetenv("GIO_EXTRA_MODULES")).split(':');
+        GIO_EXTRA_MODULES << QLatin1String(NIXPKGS_QGTK3_GIO_EXTRA_MODULES);
+        qputenv("GIO_EXTRA_MODULES", QFile::encodeName(GIO_EXTRA_MODULES.join(':')));
+#endif
+
         return new QGtk3Theme;
+    }
 
     return 0;
 }