Re-activate (known as create a new substance) a QMainWindow after the last QMainWindow is closed

[JackMyson]

As mentioned in the topic title, I have the following code.
(Note: The subclassed MainWindow and its widgets will not be shown because of the space.)

main.cpp

#include <QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
#ifdef Q_OS_DARWIN
    app.setQuitOnLastWindowClosed(false);
#endif
    MainWindow mw;
    mw.show();
    app.exec();
}

Running in macOS (I haven't built or decided to run in iOS so its fine), the application has really had a small gray dot representing the application is on work at that time; however, differ to the complex and native apps, my Qt app won't react to mouse-clicking on its icon under the dock and re-show a new MainWindow substance.

My question is, is there a public method that allows app react to icon-clicking by the users with re-create functionality enabled, in pure Qt C++ code? Thanks for reply.

[SGaist]

Hi,

Based on this feature request, you should be able to react on the ˋQEvent::ApplicationActivate`.

[mpergand]

@SGaist said in Re-activate (known as create a new substance) a QMainWindow after the last QMainWindow is closed:

Based on this feature request, you should be able to react on the ˋQEvent::ApplicationActivate`.

I'm using that in a subclass of QApplication.
The idea in pseudo code:

void Application::applicationStateChanged ( Qt::ApplicationState state)
{ 
   if(state==Qt::ApplicationActive AND
    no window is open AND
    OpenUntitledWindow )
    {
    openNewWindow();
    }

OpenUntitledWindow is a flag setting if an new window/document should be opened on startup, it works also when the app is reactivated with the code above.