Qt: QDialog - activate windows taskbar icon (C++)

Question

I just can not understand one seemingly basic thing. If we want to show our custom dialog, we can do smth like this:

OurDialog * dlg = new OurDialog; // (this);
dlg->setAttribute(Qt::WA_DeleteOnClose);

dlg->show();
dlg->activateWindow();

hide(); // hide MainWindow

Depending on giving a parent to constructor or not we can make taskbar icon visible or not. But how to make the icon not only visible but also active?

Moreover, if we move the string

hide(); // hide MainWindow

before

dlg->show();

The taskbar icon will be active, but in this case we'll get a "blinking effect" on showing the dialog. So is there any possibility to hide MainWindow, show Dialog and make the taskbar icon active?

Thank you!