Merge #9190: qt: Plug many memory leaks

ed998ea qt: Avoid OpenSSL certstore-related memory leak (Wladimir J. van der Laan)
5204598 qt: Avoid shutdownwindow-related memory leak (Wladimir J. van der Laan)
e4f126a qt: Avoid splash-screen related memory leak (Wladimir J. van der Laan)
693384e qt: Prevent thread/memory leak on exiting RPCConsole (Wladimir J. van der Laan)
47db075 qt: Plug many memory leaks (Wladimir J. van der Laan)

src/qt/addressbookpage.cpp

@@ -83,7 +83,7 @@ AddressBookPage::AddressBookPage(const PlatformStyle *platformStyle, Mode _mode,
     deleteAction = new QAction(ui->deleteAddress->text(), this);
 
     // Build context menu
-    contextMenu = new QMenu();
+    contextMenu = new QMenu(this);
     contextMenu->addAction(copyAddressAction);
     contextMenu->addAction(copyLabelAction);
     contextMenu->addAction(editAction);

src/qt/bantablemodel.cpp

@@ -87,7 +87,7 @@ BanTableModel::BanTableModel(ClientModel *parent) :
     clientModel(parent)
 {
     columns << tr("IP/Netmask") << tr("Banned Until");
-    priv = new BanTablePriv();
+    priv.reset(new BanTablePriv());
     // default to unsorted
     priv->sortColumn = -1;
 
@@ -95,6 +95,11 @@ BanTableModel::BanTableModel(ClientModel *parent) :
     refresh();
 }
 
+BanTableModel::~BanTableModel()
+{
+    // Intentionally left empty
+}
+
 int BanTableModel::rowCount(const QModelIndex &parent) const
 {
     Q_UNUSED(parent);

src/qt/bantablemodel.h

@@ -40,6 +40,7 @@ class BanTableModel : public QAbstractTableModel
 
 public:
     explicit BanTableModel(ClientModel *parent = 0);
+    ~BanTableModel();
     void startAutoRefresh();
     void stopAutoRefresh();
 
@@ -66,7 +67,7 @@ public Q_SLOTS:
 private:
     ClientModel *clientModel;
     QStringList columns;
-    BanTablePriv *priv;
+    std::unique_ptr<BanTablePriv> priv;
 };
 
 #endif // BITCOIN_QT_BANTABLEMODEL_H

src/qt/bitcoin.cpp

@@ -245,6 +245,7 @@ private:
 #endif
     int returnValue;
     const PlatformStyle *platformStyle;
+    std::unique_ptr<QWidget> shutdownWindow;
 
     void startThread();
 };
@@ -365,9 +366,8 @@ void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
 void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
 {
     SplashScreen *splash = new SplashScreen(0, networkStyle);
-    // We don't hold a direct pointer to the splash screen after creation, so use
-    // Qt::WA_DeleteOnClose to make sure that the window will be deleted eventually.
-    splash->setAttribute(Qt::WA_DeleteOnClose);
+    // We don't hold a direct pointer to the splash screen after creation, but the splash
+    // screen will take care of deleting itself when slotFinish happens.
     splash->show();
     connect(this, SIGNAL(splashFinished(QWidget*)), splash, SLOT(slotFinish(QWidget*)));
     connect(this, SIGNAL(requestedShutdown()), splash, SLOT(close()));
@@ -409,6 +409,11 @@ void BitcoinApplication::requestInitialize()
 
 void BitcoinApplication::requestShutdown()
 {
+    // Show a simple window indicating shutdown status
+    // Do this first as some of the steps may take some time below,
+    // for example the RPC console may still be executing a command.
+    shutdownWindow.reset(ShutdownWindow::showShutdownWindow(window));
+
     qDebug() << __func__ << ": Requesting shutdown";
     startThread();
     window->hide();
@@ -423,9 +428,6 @@ void BitcoinApplication::requestShutdown()
     delete clientModel;
     clientModel = 0;
 
-    // Show a simple window indicating shutdown status
-    ShutdownWindow::showShutdownWindow(window);
-
     // Request shutdown from core thread
     Q_EMIT requestedShutdown();
 }

src/qt/bitcoingui.cpp

@@ -511,6 +511,13 @@ void BitcoinGUI::setClientModel(ClientModel *_clientModel)
             // Disable context menu on tray icon
             trayIconMenu->clear();
         }
+        // Propagate cleared model to child objects
+        rpcConsole->setClientModel(nullptr);
+#ifdef ENABLE_WALLET
+        walletFrame->setClientModel(nullptr);
+#endif // ENABLE_WALLET
+        unitDisplayControl->setOptionsModel(nullptr);
+        connectionsControl->setClientModel(nullptr);
     }
 }
 
@@ -1191,7 +1198,7 @@ void UnitDisplayStatusBarControl::mousePressEvent(QMouseEvent *event)
 /** Creates context menu, its actions, and wires up all the relevant signals for mouse events. */
 void UnitDisplayStatusBarControl::createContextMenu()
 {
-    menu = new QMenu();
+    menu = new QMenu(this);
     Q_FOREACH(BitcoinUnits::Unit u, BitcoinUnits::availableUnits())
     {
         QAction *menuAction = new QAction(QString(BitcoinUnits::name(u)), this);
@@ -1248,7 +1255,5 @@ void NetworkToggleStatusBarControl::mousePressEvent(QMouseEvent *event)
 /** Lets the control know about the Client Model */
 void NetworkToggleStatusBarControl::setClientModel(ClientModel *_clientModel)
 {
-    if (_clientModel) {
-        this->clientModel = _clientModel;
-    }
+    this->clientModel = _clientModel;
 }

src/qt/coincontroldialog.cpp

@@ -59,7 +59,7 @@ CoinControlDialog::CoinControlDialog(const PlatformStyle *_platformStyle, QWidge
              unlockAction = new QAction(tr("Unlock unspent"), this);                    // we need to enable/disable this
 
     // context menu
-    contextMenu = new QMenu();
+    contextMenu = new QMenu(this);
     contextMenu->addAction(copyAddressAction);
     contextMenu->addAction(copyLabelAction);
     contextMenu->addAction(copyAmountAction);

src/qt/guiutil.cpp

@@ -585,7 +585,8 @@ void TableViewLastColumnResizingFixer::on_geometriesChanged()
  * Initializes all internal variables and prepares the
  * the resize modes of the last 2 columns of the table and
  */
-TableViewLastColumnResizingFixer::TableViewLastColumnResizingFixer(QTableView* table, int lastColMinimumWidth, int allColsMinimumWidth) :
+TableViewLastColumnResizingFixer::TableViewLastColumnResizingFixer(QTableView* table, int lastColMinimumWidth, int allColsMinimumWidth, QObject *parent) :
+    QObject(parent),
     tableView(table),
     lastColumnMinimumWidth(lastColMinimumWidth),
     allColumnsMinimumWidth(allColsMinimumWidth)

src/qt/guiutil.h

@@ -149,7 +149,7 @@ namespace GUIUtil
         Q_OBJECT
 
         public:
-            TableViewLastColumnResizingFixer(QTableView* table, int lastColMinimumWidth, int allColsMinimumWidth);
+            TableViewLastColumnResizingFixer(QTableView* table, int lastColMinimumWidth, int allColsMinimumWidth, QObject *parent);
             void stretchColumnWidth(int column);
 
         private:

src/qt/overviewpage.cpp

@@ -25,8 +25,8 @@ class TxViewDelegate : public QAbstractItemDelegate
 {
     Q_OBJECT
 public:
-    TxViewDelegate(const PlatformStyle *_platformStyle):
-        QAbstractItemDelegate(), unit(BitcoinUnits::BTC),
+    TxViewDelegate(const PlatformStyle *_platformStyle, QObject *parent=nullptr):
+        QAbstractItemDelegate(parent), unit(BitcoinUnits::BTC),
         platformStyle(_platformStyle)
     {
 
@@ -119,8 +119,7 @@ OverviewPage::OverviewPage(const PlatformStyle *platformStyle, QWidget *parent)
     currentWatchOnlyBalance(-1),
     currentWatchUnconfBalance(-1),
     currentWatchImmatureBalance(-1),
-    txdelegate(new TxViewDelegate(platformStyle)),
-    filter(0)
+    txdelegate(new TxViewDelegate(platformStyle, this))
 {
     ui->setupUi(this);
 
@@ -220,7 +219,7 @@ void OverviewPage::setWalletModel(WalletModel *model)
     if(model && model->getOptionsModel())
     {
         // Set up transaction list
-        filter = new TransactionFilterProxy();
+        filter.reset(new TransactionFilterProxy());
         filter->setSourceModel(model->getTransactionTableModel());
         filter->setLimit(NUM_ITEMS);
         filter->setDynamicSortFilter(true);
@@ -228,7 +227,7 @@ void OverviewPage::setWalletModel(WalletModel *model)
         filter->setShowInactive(false);
         filter->sort(TransactionTableModel::Date, Qt::DescendingOrder);
 
-        ui->listTransactions->setModel(filter);
+        ui->listTransactions->setModel(filter.get());
         ui->listTransactions->setModelColumn(TransactionTableModel::ToAddress);
 
         // Keep up to date with wallet

src/qt/overviewpage.h

@@ -8,6 +8,7 @@
 #include "amount.h"
 
 #include <QWidget>
+#include <memory>
 
 class ClientModel;
 class TransactionFilterProxy;
@@ -56,7 +57,7 @@ private:
     CAmount currentWatchImmatureBalance;
 
     TxViewDelegate *txdelegate;
-    TransactionFilterProxy *filter;
+    std::unique_ptr<TransactionFilterProxy> filter;
 
 private Q_SLOTS:
     void updateDisplayUnit();

src/qt/paymentserver.cpp

@@ -58,14 +58,19 @@ const char* BIP71_MIMETYPE_PAYMENTREQUEST = "application/bitcoin-paymentrequest"
 // BIP70 max payment request size in bytes (DoS protection)
 const qint64 BIP70_MAX_PAYMENTREQUEST_SIZE = 50000;
 
-X509_STORE* PaymentServer::certStore = NULL;
-void PaymentServer::freeCertStore()
+struct X509StoreDeleter {
+      void operator()(X509_STORE* b) {
+          X509_STORE_free(b);
+      }
+};
+
+struct X509Deleter {
+      void operator()(X509* b) { X509_free(b); }
+};
+
+namespace // Anon namespace
 {
-    if (PaymentServer::certStore != NULL)
-    {
-        X509_STORE_free(PaymentServer::certStore);
-        PaymentServer::certStore = NULL;
-    }
+    std::unique_ptr<X509_STORE, X509StoreDeleter> certStore;
 }
 
 //
@@ -107,20 +112,15 @@ static void ReportInvalidCertificate(const QSslCertificate& cert)
 //
 void PaymentServer::LoadRootCAs(X509_STORE* _store)
 {
-    if (PaymentServer::certStore == NULL)
-        atexit(PaymentServer::freeCertStore);
-    else
-        freeCertStore();
-
     // Unit tests mostly use this, to pass in fake root CAs:
     if (_store)
     {
-        PaymentServer::certStore = _store;
+        certStore.reset(_store);
         return;
     }
 
     // Normal execution, use either -rootcertificates or system certs:
-    PaymentServer::certStore = X509_STORE_new();
+    certStore.reset(X509_STORE_new());
 
     // Note: use "-system-" default here so that users can pass -rootcertificates=""
     // and get 'I don't like X.509 certificates, don't trust anybody' behavior:
@@ -167,11 +167,11 @@ void PaymentServer::LoadRootCAs(X509_STORE* _store)
         QByteArray certData = cert.toDer();
         const unsigned char *data = (const unsigned char *)certData.data();
 
-        X509* x509 = d2i_X509(0, &data, certData.size());
-        if (x509 && X509_STORE_add_cert(PaymentServer::certStore, x509))
+        std::unique_ptr<X509, X509Deleter> x509(d2i_X509(0, &data, certData.size()));
+        if (x509 && X509_STORE_add_cert(certStore.get(), x509.get()))
         {
-            // Note: X509_STORE_free will free the X509* objects when
-            // the PaymentServer is destroyed
+            // Note: X509_STORE increases the reference count to the X509 object,
+            // we still have to release our reference to it.
             ++nRootCerts;
         }
         else
@@ -550,7 +550,7 @@ bool PaymentServer::processPaymentRequest(const PaymentRequestPlus& request, Sen
     recipient.paymentRequest = request;
     recipient.message = GUIUtil::HtmlEscape(request.getDetails().memo());
 
-    request.getMerchant(PaymentServer::certStore, recipient.authenticatedMerchant);
+    request.getMerchant(certStore.get(), recipient.authenticatedMerchant);
 
     QList<std::pair<CScript, CAmount> > sendingTos = request.getPayTo();
     QStringList addresses;
@@ -807,3 +807,8 @@ bool PaymentServer::verifyAmount(const CAmount& requestAmount)
     }
     return fVerified;
 }
+
+X509_STORE* PaymentServer::getCertStore()
+{
+    return certStore.get();
+}

src/qt/paymentserver.h

@@ -83,7 +83,7 @@ public:
     static void LoadRootCAs(X509_STORE* store = NULL);
 
     // Return certificate store
-    static X509_STORE* getCertStore() { return certStore; }
+    static X509_STORE* getCertStore();
 
     // OptionsModel is used for getting proxy settings and display unit
     void setOptionsModel(OptionsModel *optionsModel);
@@ -140,9 +140,6 @@ private:
     bool saveURIs;                      // true during startup
     QLocalServer* uriServer;
 
-    static X509_STORE* certStore;       // Trusted root certificates
-    static void freeCertStore();
-
     QNetworkAccessManager* netManager;  // Used to fetch payment requests
 
     OptionsModel *optionsModel;

src/qt/peertablemodel.cpp

@@ -114,12 +114,12 @@ PeerTableModel::PeerTableModel(ClientModel *parent) :
     timer(0)
 {
     columns << tr("NodeId") << tr("Node/Service") << tr("User Agent") << tr("Ping");
-    priv = new PeerTablePriv();
+    priv.reset(new PeerTablePriv());
     // default to unsorted
     priv->sortColumn = -1;
 
     // set up timer for auto refresh
-    timer = new QTimer();
+    timer = new QTimer(this);
     connect(timer, SIGNAL(timeout()), SLOT(refresh()));
     timer->setInterval(MODEL_UPDATE_DELAY);
 
@@ -127,6 +127,11 @@ PeerTableModel::PeerTableModel(ClientModel *parent) :
     refresh();
 }
 
+PeerTableModel::~PeerTableModel()
+{
+    // Intentionally left empty
+}
+
 void PeerTableModel::startAutoRefresh()
 {
     timer->start();

src/qt/peertablemodel.h

@@ -46,6 +46,7 @@ class PeerTableModel : public QAbstractTableModel
 
 public:
     explicit PeerTableModel(ClientModel *parent = 0);
+    ~PeerTableModel();
     const CNodeCombinedStats *getNodeStats(int idx);
     int getRowByNodeId(NodeId nodeid);
     void startAutoRefresh();
@@ -75,7 +76,7 @@ public Q_SLOTS:
 private:
     ClientModel *clientModel;
     QStringList columns;
-    PeerTablePriv *priv;
+    std::unique_ptr<PeerTablePriv> priv;
     QTimer *timer;
 };
 

src/qt/receivecoinsdialog.cpp

@@ -25,6 +25,7 @@
 ReceiveCoinsDialog::ReceiveCoinsDialog(const PlatformStyle *_platformStyle, QWidget *parent) :
     QDialog(parent),
     ui(new Ui::ReceiveCoinsDialog),
+    columnResizingFixer(0),
     model(0),
     platformStyle(_platformStyle)
 {
@@ -49,7 +50,7 @@ ReceiveCoinsDialog::ReceiveCoinsDialog(const PlatformStyle *_platformStyle, QWid
     QAction *copyAmountAction = new QAction(tr("Copy amount"), this);
 
     // context menu
-    contextMenu = new QMenu();
+    contextMenu = new QMenu(this);
     contextMenu->addAction(copyURIAction);
     contextMenu->addAction(copyLabelAction);
     contextMenu->addAction(copyMessageAction);
@@ -91,7 +92,7 @@ void ReceiveCoinsDialog::setModel(WalletModel *_model)
             SIGNAL(selectionChanged(QItemSelection, QItemSelection)), this,
             SLOT(recentRequestsView_selectionChanged(QItemSelection, QItemSelection)));
         // Last 2 columns are set by the columnResizingFixer, when the table geometry is ready.
-        columnResizingFixer = new GUIUtil::TableViewLastColumnResizingFixer(tableView, AMOUNT_MINIMUM_COLUMN_WIDTH, DATE_COLUMN_WIDTH);
+        columnResizingFixer = new GUIUtil::TableViewLastColumnResizingFixer(tableView, AMOUNT_MINIMUM_COLUMN_WIDTH, DATE_COLUMN_WIDTH, this);
     }
 }
 

src/qt/receiverequestdialog.cpp

@@ -32,7 +32,7 @@
 QRImageWidget::QRImageWidget(QWidget *parent):
     QLabel(parent), contextMenu(0)
 {
-    contextMenu = new QMenu();
+    contextMenu = new QMenu(this);
     QAction *saveImageAction = new QAction(tr("&Save Image..."), this);
     connect(saveImageAction, SIGNAL(triggered()), this, SLOT(saveImage()));
     contextMenu->addAction(saveImageAction);

src/qt/recentrequeststablemodel.cpp

@@ -14,7 +14,7 @@
 #include <boost/foreach.hpp>
 
 RecentRequestsTableModel::RecentRequestsTableModel(CWallet *wallet, WalletModel *parent) :
-    walletModel(parent)
+    QAbstractTableModel(parent), walletModel(parent)
 {
     Q_UNUSED(wallet);
     nReceiveRequestsMaxId = 0;

src/qt/rpcconsole.cpp

@@ -382,7 +382,6 @@ RPCConsole::RPCConsole(const PlatformStyle *_platformStyle, QWidget *parent) :
     // based timer interface
     RPCSetTimerInterfaceIfUnset(rpcTimerInterface);
 
-    startExecutor();
     setTrafficGraphRange(INITIAL_TRAFFIC_GRAPH_MINS);
 
     ui->detailWidget->hide();
@@ -396,7 +395,6 @@ RPCConsole::RPCConsole(const PlatformStyle *_platformStyle, QWidget *parent) :
 RPCConsole::~RPCConsole()
 {
     GUIUtil::saveWindowGeometry("nRPCConsoleWindow", this);
-    Q_EMIT stopExecutor();
     RPCUnsetTimerInterface(rpcTimerInterface);
     delete rpcTimerInterface;
     delete ui;
@@ -486,7 +484,7 @@ void RPCConsole::setClientModel(ClientModel *model)
         QAction* banAction365d    = new QAction(tr("Ban for") + " " + tr("1 &year"), this);
 
         // create peer table context menu
-        peersTableContextMenu = new QMenu();
+        peersTableContextMenu = new QMenu(this);
         peersTableContextMenu->addAction(disconnectAction);
         peersTableContextMenu->addAction(banAction1h);
         peersTableContextMenu->addAction(banAction24h);
@@ -534,7 +532,7 @@ void RPCConsole::setClientModel(ClientModel *model)
         QAction* unbanAction = new QAction(tr("&Unban"), this);
 
         // create ban table context menu
-        banTableContextMenu = new QMenu();
+        banTableContextMenu = new QMenu(this);
         banTableContextMenu->addAction(unbanAction);
 
         // ban table context menu signals
@@ -565,6 +563,14 @@ void RPCConsole::setClientModel(ClientModel *model)
         autoCompleter = new QCompleter(wordList, this);
         ui->lineEdit->setCompleter(autoCompleter);
         autoCompleter->popup()->installEventFilter(this);
+        // Start thread to execute RPC commands.
+        startExecutor();
+    }
+    if (!model) {
+        // Client model is being set to 0, this means shutdown() is about to be called.
+        // Make sure we clean up the executor thread
+        Q_EMIT stopExecutor();
+        thread.wait();
     }
 }
 
@@ -759,9 +765,8 @@ void RPCConsole::browseHistory(int offset)
 
 void RPCConsole::startExecutor()
 {
-    QThread *thread = new QThread;
     RPCExecutor *executor = new RPCExecutor();
-    executor->moveToThread(thread);
+    executor->moveToThread(&thread);
 
     // Replies from executor object must go to this object
     connect(executor, SIGNAL(reply(int,QString)), this, SLOT(message(int,QString)));
@@ -769,16 +774,15 @@ void RPCConsole::startExecutor()
     connect(this, SIGNAL(cmdRequest(QString)), executor, SLOT(request(QString)));
 
     // On stopExecutor signal
-    // - queue executor for deletion (in execution thread)
     // - quit the Qt event loop in the execution thread
-    connect(this, SIGNAL(stopExecutor()), executor, SLOT(deleteLater()));
-    connect(this, SIGNAL(stopExecutor()), thread, SLOT(quit()));
-    // Queue the thread for deletion (in this thread) when it is finished
-    connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
+    connect(this, SIGNAL(stopExecutor()), &thread, SLOT(quit()));
+    // - queue executor for deletion (in execution thread)
+    connect(&thread, SIGNAL(finished()), executor, SLOT(deleteLater()), Qt::DirectConnection);
+    connect(&thread, SIGNAL(finished()), this, SLOT(test()), Qt::DirectConnection);
 
     // Default implementation of QThread::run() simply spins up an event loop in the thread,
     // which is what we want.
-    thread->start();
+    thread.start();
 }
 
 void RPCConsole::on_tabWidget_currentChanged(int index)

src/qt/rpcconsole.h

@@ -12,6 +12,7 @@
 
 #include <QWidget>
 #include <QCompleter>
+#include <QThread>
 
 class ClientModel;
 class PlatformStyle;
@@ -148,6 +149,7 @@ private:
     QMenu *banTableContextMenu;
     int consoleFontSize;
     QCompleter *autoCompleter;
+    QThread thread;
 
     /** Update UI with latest network info from model. */
     void updateNetworkState();

src/qt/splashscreen.cpp

@@ -147,6 +147,7 @@ void SplashScreen::slotFinish(QWidget *mainWin)
     if (isMinimized())
         showNormal();
     hide();
+    deleteLater(); // No more need for this
 }
 
 static void InitMessage(SplashScreen *splash, const std::string &message)

src/qt/transactionview.cpp

@@ -37,7 +37,7 @@
 
 TransactionView::TransactionView(const PlatformStyle *platformStyle, QWidget *parent) :
     QWidget(parent), model(0), transactionProxyModel(0),
-    transactionView(0), abandonAction(0)
+    transactionView(0), abandonAction(0), columnResizingFixer(0)
 {
     // Build filter row
     setContentsMargins(0,0,0,0);
@@ -147,7 +147,7 @@ TransactionView::TransactionView(const PlatformStyle *platformStyle, QWidget *pa
     QAction *editLabelAction = new QAction(tr("Edit label"), this);
     QAction *showDetailsAction = new QAction(tr("Show transaction details"), this);
 
-    contextMenu = new QMenu();
+    contextMenu = new QMenu(this);
     contextMenu->addAction(copyAddressAction);
     contextMenu->addAction(copyLabelAction);
     contextMenu->addAction(copyAmountAction);
@@ -212,7 +212,7 @@ void TransactionView::setModel(WalletModel *_model)
         transactionView->setColumnWidth(TransactionTableModel::Type, TYPE_COLUMN_WIDTH);
         transactionView->setColumnWidth(TransactionTableModel::Amount, AMOUNT_MINIMUM_COLUMN_WIDTH);
 
-        columnResizingFixer = new GUIUtil::TableViewLastColumnResizingFixer(transactionView, AMOUNT_MINIMUM_COLUMN_WIDTH, MINIMUM_COLUMN_WIDTH);
+        columnResizingFixer = new GUIUtil::TableViewLastColumnResizingFixer(transactionView, AMOUNT_MINIMUM_COLUMN_WIDTH, MINIMUM_COLUMN_WIDTH, this);
 
         if (_model->getOptionsModel())
         {

src/qt/utilitydialog.cpp

@@ -171,22 +171,20 @@ ShutdownWindow::ShutdownWindow(QWidget *parent, Qt::WindowFlags f):
     setLayout(layout);
 }
 
-void ShutdownWindow::showShutdownWindow(BitcoinGUI *window)
+QWidget *ShutdownWindow::showShutdownWindow(BitcoinGUI *window)
 {
     if (!window)
-        return;
+        return nullptr;
 
     // Show a simple window indicating shutdown status
     QWidget *shutdownWindow = new ShutdownWindow();
-    // We don't hold a direct pointer to the shutdown window after creation, so use
-    // Qt::WA_DeleteOnClose to make sure that the window will be deleted eventually.
-    shutdownWindow->setAttribute(Qt::WA_DeleteOnClose);
     shutdownWindow->setWindowTitle(window->windowTitle());
 
     // Center shutdown window at where main window was
     const QPoint global = window->mapToGlobal(window->rect().center());
     shutdownWindow->move(global.x() - shutdownWindow->width() / 2, global.y() - shutdownWindow->height() / 2);
     shutdownWindow->show();
+    return shutdownWindow;
 }
 
 void ShutdownWindow::closeEvent(QCloseEvent *event)

src/qt/utilitydialog.h

@@ -43,7 +43,7 @@ class ShutdownWindow : public QWidget
 
 public:
     ShutdownWindow(QWidget *parent=0, Qt::WindowFlags f=0);
-    static void showShutdownWindow(BitcoinGUI *window);
+    static QWidget *showShutdownWindow(BitcoinGUI *window);
 
 protected:
     void closeEvent(QCloseEvent *event);