Mark as single-instance using X-GNOME-SingleWindow key

src/ispdb/main.cpp

@@ -63,9 +63,9 @@ int main(int argc, char **argv)
 {
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
     QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling, true);
+    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps, true);
 #endif
     QApplication app(argc, argv);
-    app.setAttribute(Qt::AA_UseHighDpiPixmaps, true);
     KAboutData aboutData(QStringLiteral("ispdb"),
                          i18n("ISPDB Assistant"),
                          QStringLiteral("0.1"),

src/org.kde.accountwizard.desktop

@@ -82,3 +82,4 @@ MimeType=application/x-accountwizard-package;
 Terminal=false
 X-DBUS-StartupType=Unique
 X-DBUS-ServiceName=org.kde.accountwizard
+X-GNOME-SingleWindow=true