Thx Martin, it works!
Not quite. Try: delete myBox; myBox = Gtk::manage(new Gtk::VBox()); myBox->pack_start(widget4); myBox->pack_start(widget5); myBox->pack_start(widget6); myBox->show_all(); // or myBox->show_all_children(). Not sure. m_scrolledParamWindow.add(*myBox); Regards, Martin