qt: Delay shutdown while a modal dialog is active

src/qt/bitcoin.cpp

@@ -268,7 +268,11 @@ void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
     connect(window, &BitcoinGUI::quitRequested, this, &BitcoinApplication::requestShutdown);
 
     pollShutdownTimer = new QTimer(window);
-    connect(pollShutdownTimer, &QTimer::timeout, window, &BitcoinGUI::detectShutdown);
+    connect(pollShutdownTimer, &QTimer::timeout, [this]{
+        if (!QApplication::activeModalWidget()) {
+            window->detectShutdown();
+        }
+    });
 }
 
 void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)