filter: intercept quit event to avoid deadlock

main.qml

@@ -100,6 +100,7 @@ ApplicationWindow {
     property bool splashDisplayedBeforeButtonRequest;
     property bool themeTransition: false
     property int backgroundSyncType: Wallet.BackgroundSync_Off;
+    property bool isQuitting: false
 
     // fiat price conversion
     property real fiatPrice: 0
@@ -282,6 +283,15 @@ ApplicationWindow {
             persistentSettings.kdfRounds);
     }
 
+    function gracefulQuit() {
+        if (isQuitting)
+            return;
+        isQuitting = true;
+        closeWallet(function() {
+            Qt.quit();
+        })
+    }
+
     function closeWallet(callback) {
 
         // Disconnect all listeners