QtMaterialDialog: dialog is invisible without calling QWidget::show()

[ZimNovich]

When I am instantiating an object of QtMaterialDialog class, the dialog becomes visible only after calling QWidget's show() method:

// Show Preferences
QtMaterialDialog* prefs = new QtMaterialDialog(this);
// Adding child objects and stuff
. . .
prefs->setWindowLayout(dialogLayout);
prefs->show(); // This call is necessary (!)
prefs->showDialog();