File libqt5-prioritise-gtk2-platformtheme.patch of Package libqt5-qtbase
diff --git a/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp b/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
index 6db25a90..4ecca608 100644
--- a/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
+++ b/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
@@ -871,7 +871,9 @@ QStringList QGenericUnixTheme::themeNames()
result.push_back(QLatin1String(QKdeTheme::name));
#endif
} else if (gtkBasedEnvironments.contains(desktopName)) {
- // prefer the GTK3 theme implementation with native dialogs etc.
+ // prefer the GTK+2 theme implementation with the native style, etc.
+ result.push_back(QStringLiteral("gtk2"));
+ // prefer second the GTK+3 theme implementation with native dialogs, etc.
result.push_back(QStringLiteral("gtk3"));
// fallback to the generic Gnome theme if loading the GTK3 theme fails
result.push_back(QLatin1String(QGnomeTheme::name));