QMessageBox::information always crashes

[Tito]

for no apparent reason, I can't get QMessageBox::information to work in my current application. It always crashes even in the simplest cases.

for example, even this causes a crash.

myAbout 	= new QAction(tr("About"), this);
	connect(myAbout, SIGNAL(triggered()), SLOT(aboutClicked()));
	#if defined(Q_OS_SYMBIAN) && defined(USE_ACTIONS)
		menuBar()->addAction(myAbout);
	#endif
 
 
void myApplication::aboutClicked()
	{
	qDebug() << "myApplication::aboutClicked()";
	QMessageBox::information ( this, APP_NAME, "Some text" );
	//QMessageBox::information ( 0, APP_NAME, "Some text" );
	}

myAbout 	= new QAction(tr("About"), this);
	connect(myAbout, SIGNAL(triggered()), SLOT(aboutClicked()));
	#if defined(Q_OS_SYMBIAN) && defined(USE_ACTIONS)
		menuBar()->addAction(myAbout);
	#endif


void myApplication::aboutClicked()
	{
	qDebug() << "myApplication::aboutClicked()";
	QMessageBox::information ( this, APP_NAME, "Some text" );
	//QMessageBox::information ( 0, APP_NAME, "Some text" );
	}

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I do have a couple of threads running, but the QMessageBox is always called from the main UI thread. Any ideas?

[e8johan]

Could you provide a debugger backtrace from the crash?

[cloaked_and_coastin]

Should your connect have 4 arguments instead of 3?

Instead of:
connect(myAbout, SIGNAL(triggered()), SLOT(aboutClicked()));

try:
connect(myAbout, SIGNAL(triggered()), myAbout, SLOT(aboutClicked()));

Hope this helps.

[Lykurg]

As Tito said, the connection works and

connect(myAbout, SIGNAL(triggered()), SLOT(aboutClicked()));

connect(myAbout, SIGNAL(triggered()), SLOT(aboutClicked()));

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is a shorthand for

connect(myAbout, SIGNAL(triggered()), this, SLOT(aboutClicked()));

connect(myAbout, SIGNAL(triggered()), this, SLOT(aboutClicked()));

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. See QObject::connect().

[Tito]

the problem isn't with the connect.... You only need 4 arguments if the slot object is different from the signal object.

As for the error, I've simplified it even more... the messagebox is being sent up as the first thing in the mainwindow creation.. which works on a blank project, but not here..

unfortunately the debug stack isn't helpful.

Thread [Thread id: 758] (Suspended: Signal 'Exception 0' received. Description: A data abort exception has occurred..)
2 Unknown (0x7971C6FA)() 0x7971c6fa
1 Unknown (0x7971CD60)() 0x7971cd60

hmmm.....

[Tito]

And the lesson today is... don't mess with TARGET.EPOCSTACKSIZE... let Qt sort it out for itself.

Wow.. what a waste of time that was.