Communication between QThread and Yes/No QMessageBox?

[spud]

As long as the tQThread object was created in the Gui thread, you can set up a connection between a private signal and a private slot. For the synchronization you need a QWaitCondition and a QMutex.
e.g.:

class WorkingThread : public QThread
{
	Q_OBJECT
public:
	WorkingThread(QObject*parent=0);
protected:
	virtual void run();
signals:
	void askAQuestion( const QString& question, QMessageBox::StandardButton* answer);
private slots:
	void questionAsked(const QString& question, QMessageBox::StandardButton* answer);
private:
	QWaitCondition waitCondition;
	QMutex mutex;
};
 
WorkingThread::WorkingThread(QObject*parent) 
	: QThread(parent=0)
{
	connect(this, SIGNAL(askAQuestion( const QString&, QMessageBox::StandardButton*)), 
		this, SLOT(questionAsked( const QString&, QMessageBox::StandardButton*)));
}
 
void WorkingThread::run()
{
	QMessageBox::StandardButton answer = QMessageBox::Yes;
	do
	{
		QMutexLocker locker(&mutex);
		emit askAQuestion( "do you want to continue?", &answer);
		waitCondition.wait(&mutex);
	}
	while(answer == QMessageBox::Yes);
}
 
void WorkingThread::questionAsked(const QString& question, QMessageBox::StandardButton* answer)
{
	QMutexLocker locker(&mutex);
	*answer = QMessageBox::question(0, "Question:", question, QMessageBox::Yes|QMessageBox::No);
	waitCondition.wakeOne();
}

class WorkingThread : public QThread
{
	Q_OBJECT
public:
	WorkingThread(QObject*parent=0);
protected:
	virtual void run();
signals:
	void askAQuestion( const QString& question, QMessageBox::StandardButton* answer);
private slots:
	void questionAsked(const QString& question, QMessageBox::StandardButton* answer);
private:
	QWaitCondition waitCondition;
	QMutex mutex;
};

WorkingThread::WorkingThread(QObject*parent) 
	: QThread(parent=0)
{
	connect(this, SIGNAL(askAQuestion( const QString&, QMessageBox::StandardButton*)), 
		this, SLOT(questionAsked( const QString&, QMessageBox::StandardButton*)));
}

void WorkingThread::run()
{
	QMessageBox::StandardButton answer = QMessageBox::Yes;
	do
	{
		QMutexLocker locker(&mutex);
		emit askAQuestion( "do you want to continue?", &answer);
		waitCondition.wait(&mutex);
	}
	while(answer == QMessageBox::Yes);
}

void WorkingThread::questionAsked(const QString& question, QMessageBox::StandardButton* answer)
{
	QMutexLocker locker(&mutex);
	*answer = QMessageBox::question(0, "Question:", question, QMessageBox::Yes|QMessageBox::No);
	waitCondition.wakeOne();
}

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The connection will automatically be queued since the run() function doesn't reside in the same thread as the QThread object, thus it's safe to use a messagebox.

Good luck!