How to create dialog without blocking main form?

Question

For now I can do:

void MainWindow::on_actionPATH_triggered() {
    std::unique_ptr<QDialog> win(new QDialog());
    win->exec();
}

Should I use async / run in separate threadto avoid blocking main window or is there way to subscribe to close even and delete / free object there?

Answer 1

You can use just show()

void MainWindow::on_actionPATH_triggered() {
    QDialog* win = new QDialog();
    //needed connect
    win->setAttribute(Qt::WA_DeleteOnClose);//we don't want memory leak
    win->show();
}

and use

win->setModal(false);//but it is default option, you don't need to change it

From doc:

By default, this property is false and show() pops up the dialog as modeless. Setting his property to true is equivalent to setting QWidget::windowModality to Qt::ApplicationModal. exec() ignores the value of this property and always pops up the dialog as modal.

Qt::WA_DeleteOnClose will delete your dialog, when user close it.

You can also set parent to dialog:

QDialog* win = new QDialog(this);

In this case win will be delete with your mainWindow.

Info about Qt parent child relationship

And you don't need here separate thread.