I am working on a program that can minimize to tray and hide the main window. I expect the mainwindow to show when I click on the tray icon. This usually works, but I find that if the program minimizes to tray when I call QFileDialog::getOpenFileName() to select file without closing the dialog, I cannot activate the trayicon. Does anyone know how to solve it? I am using Qt 5.12.1 on Manjaro Linux. Here is my example:

main.cpp:

Qt Code: 
  1. #include "mainwindow.h"
  2. #include <QApplication>
  3.  
  4. int main(int argc, char *argv[])
  5. {
  6.     QApplication a(argc, argv);
  7.     MainWindow w;
  8.     w.show();
  9.  
  10.     return a.exec();
  11. }
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mainwindow.h:

Qt Code: 
  1. class MainWindow : public QMainWindow
  2. {
  3.     Q_OBJECT
  4.     QSystemTrayIcon *trayIcon;
  5.     QMenu *trayContextMenu;
  6.     QAction *actShow;
  7.     QPushButton *button;
  8.  
  9. public:
  10.     MainWindow(QWidget *parent = 0);
  11.  
  12. protected:
  13.     void changeEvent(QEvent *);
  14.  
  15. private slots:
  16.     void click();
  17.     void trayIcon_activated(QSystemTrayIcon::ActivationReason reason);
  18.     void actShow_Triggered();
  19. };
  20.  
  21. #endif // MAINWINDOW_H
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mainwindow.cpp:

Qt Code: 
  1. #include "mainwindow.h"
  2. #include <QFileDialog>
  3.  
  4. MainWindow::MainWindow(QWidget *parent) :
  5.     QMainWindow(parent)
  6. {
  7.     QPushButton *button = new QPushButton("button", this);
  8.     setCentralWidget(button);
  9.     connect(button,&QPushButton::clicked,
  10.             this,&MainWindow::click);
  11.     trayIcon=new QSystemTrayIcon;
  12.     trayIcon->setIcon(QIcon("hmtimer.png"));
  13.     trayContextMenu=new QMenu;
  14.     actShow=trayContextMenu->addAction(tr("Show"));
  15.     trayIcon->setContextMenu(trayContextMenu);
  16.     connect(actShow,&QAction::triggered,
  17.             this,&MainWindow::actShow_Triggered);
  18.     connect(trayIcon,&QSystemTrayIcon::activated,
  19.             this,&MainWindow::trayIcon_activated);
  20. }
  21.  
  22. void MainWindow::changeEvent(QEvent *event)
  23. {
  24.     if(event->type()==QEvent::WindowStateChange){
  25.         if(isMinimized()){
  26.             this->hide();
  27.             trayIcon->show();
  28.         }
  29.     }
  30.     else{
  31.         QMainWindow::changeEvent(event);
  32.     }
  33. }
  34.  
  35. void MainWindow::click()
  36. {
  37.     QFileDialog::getOpenFileName(this,QString());
  38. }
  39.  
  40. void MainWindow::trayIcon_activated(QSystemTrayIcon::ActivationReason reason)
  41. {
  42.     if(reason==3){ //reason==Trigger
  43.         this->show();
  44.         trayIcon->hide();
  45.     }
  46. }
  47.  
  48. void MainWindow::actShow_Triggered()
  49. {
  50.     this->show();
  51.     trayIcon->hide();
  52. }
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The example can be downloaded here

It seems that if the program minimizes to tray when QFileDialog::getOpenFileName(this,QString()) is not closed, I cannot make the mainwindow appear by click on the tray icon or right click to show the context menu.

How to reproduce:

1. Open the program
2. Click on the button to open file dialog
3. Minimize to tray
4. Try clicking and right-clicking on the tray icon