How to get focus back to main window if non-modal dialog is closed?

[ChrisW67]

I don't know what this "hide" button is. The dialog title bar has a close button, that does exactly what it is advertised to do. It calls the closeEvent(), which you were claiming it did not do. If that event is accepted (the default) then, to quote the QCloseEvent docs (emphasis mine):

Close events contain a flag that indicates whether the receiver wants the widget to be closed or not. When a widget accepts the close event, it is hidden (and destroyed if it was created with the Qt::WA_DeleteOnClose flag).

The corollary is that the dialog is not deleted on close if the Qt::WA_DeleteOnClose attribute is not set. The Qt::WA_DeleteOnClose is set only so the memory is not leaked if you close the parent-less dialog because you cannot rely a QObject parent to do it for you. If you want a mode-less top-level dialog that doesn't delete itself on close then leave out the attribute, but you have to manage the object lifetime elsewhere. Qt::WA_DeleteOnClose has no effect on whether the closeEvent() is called.

To make the whole application quit if the main window is closed then create the mode-less dialog as a child of the main window. There's no magic here.

This example demonstrates your requirement. Take careful note of when the dialog is destroyed.

• Hides when its close button is clicked
• Hides when its "Hide Me" button is clicked
• Shows when the main window calls show()
• Is not considered a top-level window that stops the main event loop exiting

#include <QtGui>
#include <QDebug>
 
class Dialog: public QDialog {
    Q_OBJECT
public:
    Dialog(QWidget *p = 0): QDialog(p) {
        qDebug() << this << "created";
        QPushButton *pb = new QPushButton("Hide Me", this);
        connect(pb, SIGNAL(clicked()), this, SLOT(hide()));
        QVBoxLayout *layout = new QVBoxLayout;
        layout->addWidget(pb);
        setLayout(layout);
    }
    ~Dialog() { 
        qDebug() << this << "destroyed"; 
    }
protected:
    void closeEvent(QCloseEvent *e) { qDebug() << this << "closeEvent called"; }
};
 
class MainWindow: public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *p = 0): QMainWindow(p), dialog(0) {
        QPushButton *pb = new QPushButton("Show dialog", this);
        connect(pb, SIGNAL(clicked()), this, SLOT(openDialog()));
        setCentralWidget(pb);
    }
    ~MainWindow() { qDebug() << "MainWindow destroyed:" << this; }
public slots:
    void openDialog() {
        if (!dialog)
            dialog = new Dialog(this); 
        dialog->show();
    }
protected:
    void closeEvent(QCloseEvent *e) {
        qDebug() << this << "closeEvent called";
    }
private:
    Dialog *dialog;
};
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    MainWindow m;
    m.show();
    return app.exec();
}
#include "main.moc"

#include <QtGui>
#include <QDebug>

class Dialog: public QDialog {
    Q_OBJECT
public:
    Dialog(QWidget *p = 0): QDialog(p) {
        qDebug() << this << "created";
        QPushButton *pb = new QPushButton("Hide Me", this);
        connect(pb, SIGNAL(clicked()), this, SLOT(hide()));
        QVBoxLayout *layout = new QVBoxLayout;
        layout->addWidget(pb);
        setLayout(layout);
    }
    ~Dialog() { 
        qDebug() << this << "destroyed"; 
    }
protected:
    void closeEvent(QCloseEvent *e) { qDebug() << this << "closeEvent called"; }
};

class MainWindow: public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *p = 0): QMainWindow(p), dialog(0) {
        QPushButton *pb = new QPushButton("Show dialog", this);
        connect(pb, SIGNAL(clicked()), this, SLOT(openDialog()));
        setCentralWidget(pb);
    }
    ~MainWindow() { qDebug() << "MainWindow destroyed:" << this; }
public slots:
    void openDialog() {
        if (!dialog)
            dialog = new Dialog(this); 
        dialog->show();
    }
protected:
    void closeEvent(QCloseEvent *e) {
        qDebug() << this << "closeEvent called";
    }
private:
    Dialog *dialog;
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    MainWindow m;
    m.show();
    return app.exec();
}
#include "main.moc"

To copy to clipboard, switch view to plain text mode