closeEvent preventing shutdown

[gfunk]

It seems that when I implement the QMainWindow::closeEvent() function, my application blocks shutdown -ie, when I shutdown the computer, it tries to close all the apps but chokes on my Qt app, and so it doesn't shut down. In my closeEvent() function I do create a QMessageBox to ask the user if it's okay to exit. When I remove this QMessageBox out, my app closes on shutdown correctly along with the rest of system. Wondering what might be wrong with my code...

mpMessageBox = new QMessageBox(QMessageBox::Question, "Name",
   QString(tr("Are you sure you want to exit?")),
   QMessageBox::Yes | QMessageBox::No, this);
  mpMessageBox->setModal(true);
  mpMessageBox->setAttribute(Qt::WA_DeleteOnClose);
  mpMessageBox->show();
  connect(mpMessageBox, SIGNAL(destroyed()), this, SLOT(dismissMsgBox()));

mpMessageBox = new QMessageBox(QMessageBox::Question, "Name",
   QString(tr("Are you sure you want to exit?")),
   QMessageBox::Yes | QMessageBox::No, this);
  mpMessageBox->setModal(true);
  mpMessageBox->setAttribute(Qt::WA_DeleteOnClose);
  mpMessageBox->show();
  connect(mpMessageBox, SIGNAL(destroyed()), this, SLOT(dismissMsgBox()));

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Yes, I know it's rather unorthodox to create a message box like this, but it was just so that it would not block the event loop, while still having a modal dialog.

[ToddAtWSU]

I don't know if this will make much difference but have you tried making your connect statement before executing your show command? Since you use show( ) I would think this wouldn't be the problem, but I like to connect all signals and slots before showing a dialog. If this doesn't work, could you show the code inside your dismissMsgBox( ) SLOT?

I just looked in the Qt docs and the SIGNAL destroyed for a QObject says it passes a QObject* as an argument in the SIGNAL so I am guessing you are not capturing the signal since you are trying to get a signal with no arguments. The code should look like:

connect( mpMessageBox, SIGNAL( destroyed( QObject* ) ), this, SLOT( dismissMsgBox( QObject* ) ) );

connect( mpMessageBox, SIGNAL( destroyed( QObject* ) ), this, SLOT( dismissMsgBox( QObject* ) ) );

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Do either of these suggestions work?

[niko]

Why don't you use exec() instead of show()?
This way you wouldn't need any signals and slots at all.