MainWindow disappearing when loading a QMessageBox

[fabietto]

Dear all,

I'm experiencing a strange issue, never happened to me before.

In a class of my application I've created a simple SIGNAL-SLOT mechanism to manage the pressing of the "Exit" button by the user:

// Exit buttons
QObject::connect(mainWindow->pushButton_Exit, SIGNAL(released()), this, SLOT(exitApplication()));
QObject::connect(this, SIGNAL(confirmClosing()), qApp, SLOT(quit()));

// Exit buttons
QObject::connect(mainWindow->pushButton_Exit, SIGNAL(released()), this, SLOT(exitApplication()));
QObject::connect(this, SIGNAL(confirmClosing()), qApp, SLOT(quit()));

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mainWindow is obviously the main window of my application, defined as a member of a class created through the designer (and then made child of QMainWindow).

The exitApplication() slot provides to prompt the user with a QMessageBox, asking him to confirm the exiting:

// Show a dialog box asking confirmation to the user
int reply;
reply = QMessageBox::warning(this, tr("Application exit"),
            tr("An evolution is in progress.\nAre you really sure you want to exit now?"),           
            QMessageBox::No | QMessageBox::Default, QMessageBox::Yes | 
            QMessageBox::Escape);

// Show a dialog box asking confirmation to the user
int reply;
reply = QMessageBox::warning(this, tr("Application exit"),
            tr("An evolution is in progress.\nAre you really sure you want to exit now?"),           
            QMessageBox::No | QMessageBox::Default, QMessageBox::Yes | 
            QMessageBox::Escape);

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(the code continue with something like: if yes then ::exit(0))

The problem is that, when this QMessageBox appears, the application's main window disappears. Even if I press "No" on the dialog, the main window doesn't re-appears. The application still runs.

Any clue about the reason of this behaviour?

Many thanks,
Fabio