Fix minimized window bug on Linux

On some Linux systems the minimized to the taskbar (iconified) main
window cannot be restored properly using actions from the systray icon
menu when QSystemTrayIcon::contextMenu() is a child of the main window.

src/qt/bitcoingui.cpp

@@ -36,6 +36,7 @@
 #include <util/system.h>
 
 #include <iostream>
+#include <memory>
 
 #include <QAction>
 #include <QApplication>
@@ -44,6 +45,7 @@
 #include <QDesktopWidget>
 #include <QDragEnterEvent>
 #include <QListWidget>
+#include <QMenu>
 #include <QMenuBar>
 #include <QMessageBox>
 #include <QMimeData>
@@ -53,6 +55,7 @@
 #include <QStackedWidget>
 #include <QStatusBar>
 #include <QStyle>
+#include <QSystemTrayIcon>
 #include <QTimer>
 #include <QToolBar>
 #include <QUrlQuery>
@@ -73,6 +76,7 @@ const std::string BitcoinGUI::DEFAULT_UIPLATFORM =
 BitcoinGUI::BitcoinGUI(interfaces::Node& node, const PlatformStyle *_platformStyle, const NetworkStyle *networkStyle, QWidget *parent) :
  QMainWindow(parent),
  m_node(node),
+ trayIconMenu{new QMenu()},
  platformStyle(_platformStyle)
 {
  QSettings settings;
@@ -610,16 +614,12 @@ void BitcoinGUI::createTrayIconMenu()
  if (!trayIcon)
  return;
 
- trayIconMenu = new QMenu(this);
- trayIcon->setContextMenu(trayIconMenu);
-
+ trayIcon->setContextMenu(trayIconMenu.get());
  connect(trayIcon, &QSystemTrayIcon::activated, this, &BitcoinGUI::trayIconActivated);
 #else
  // Note: On macOS, the Dock icon is used to provide the tray's functionality.
  MacDockIconHandler *dockIconHandler = MacDockIconHandler::instance();
  connect(dockIconHandler, &MacDockIconHandler::dockIconClicked, this, &BitcoinGUI::macosDockIconActivated);
-
- trayIconMenu = new QMenu(this);
  trayIconMenu->setAsDockMenu();
 #endif
 

src/qt/bitcoingui.h

@@ -16,7 +16,6 @@
 #include <QLabel>
 #include <QMainWindow>
 #include <QMap>
-#include <QMenu>
 #include <QPoint>
 #include <QSystemTrayIcon>
 
@@ -47,6 +46,7 @@ class Node;
 QT_BEGIN_NAMESPACE
 class QAction;
 class QComboBox;
+class QMenu;
 class QProgressBar;
 class QProgressDialog;
 QT_END_NAMESPACE
@@ -141,7 +141,7 @@ class BitcoinGUI : public QMainWindow
  QComboBox* m_wallet_selector = nullptr;
 
  QSystemTrayIcon* trayIcon = nullptr;
- QMenu* trayIconMenu = nullptr;
+ const std::unique_ptr<QMenu> trayIconMenu;
  Notificator* notificator = nullptr;
  RPCConsole* rpcConsole = nullptr;
  HelpMessageDialog* helpMessageDialog = nullptr;