gui: Delete progress dialog instead of hidding it

src/qt/walletcontroller.cpp

@@ -166,6 +166,7 @@ WalletControllerActivity::~WalletControllerActivity()
 
 void WalletControllerActivity::showProgressDialog(const QString& label_text)
 {
+    assert(!m_progress_dialog);
     m_progress_dialog = new QProgressDialog(m_parent_widget);
 
     m_progress_dialog->setLabelText(label_text);
@@ -175,6 +176,13 @@ void WalletControllerActivity::showProgressDialog(const QString& label_text)
     GUIUtil::PolishProgressDialog(m_progress_dialog);
 }
 
+void WalletControllerActivity::destroyProgressDialog()
+{
+    assert(m_progress_dialog);
+    delete m_progress_dialog;
+    m_progress_dialog = nullptr;
+}
+
 CreateWalletActivity::CreateWalletActivity(WalletController* wallet_controller, QWidget* parent_widget)
     : WalletControllerActivity(wallet_controller, parent_widget)
 {
@@ -229,7 +237,7 @@ void CreateWalletActivity::createWallet()
 
 void CreateWalletActivity::finish()
 {
-    m_progress_dialog->hide();
+    destroyProgressDialog();
 
     if (!m_error_message.empty()) {
         QMessageBox::critical(m_parent_widget, tr("Create wallet failed"), QString::fromStdString(m_error_message));
@@ -270,7 +278,7 @@ OpenWalletActivity::OpenWalletActivity(WalletController* wallet_controller, QWid
 
 void OpenWalletActivity::finish()
 {
-    m_progress_dialog->hide();
+    destroyProgressDialog();
 
     if (!m_error_message.empty()) {
         QMessageBox::critical(m_parent_widget, tr("Open wallet failed"), QString::fromStdString(m_error_message));

src/qt/walletcontroller.h

@@ -96,6 +96,7 @@ protected:
     QObject* worker() const { return m_wallet_controller->m_activity_worker; }
 
     void showProgressDialog(const QString& label_text);
+    void destroyProgressDialog();
 
     WalletController* const m_wallet_controller;
     QWidget* const m_parent_widget;