How can I access the Gtk.Box in Gtk.Dialog? - gtk3

Question

I get an error (Gtk-WARNING **: 18:33:56.632: Attempting to add a widget with type GtkBox to a GtkDialog, but as a GtkBin subclass a GtkDialog can only contain one widget at a time; it already contains a widget of type GtkBox)
when executing this code:
def switchfile(self, widget):
self.cd = None
self.cd = {
'win' : Gtk.Dialog(),
'entry' : Gtk.Entry(),
'btnok' : Gtk.Button.new_from_icon_name("document-open-symbolic", Gtk.IconSize.MENU),
'label' : Gtk.Label(),
'vbox' : Gtk.Box(orientation=Gtk.Orientation.VERTICAL),
'hbox' : Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL)
}
self.cd['entry'].set_placeholder_text('Notebook Name')
self.cd['btnok'].connect('clicked', self.switch_yes)
self.cd['hbox'].pack_start(self.cd['entry'], True, True, 0)
self.cd['hbox'].pack_start(self.cd['btnok'], True, True, 0)
self.cd['vbox'].pack_start(self.cd['label'], True, True, 0)
self.cd['vbox'].pack_start(self.cd['hbox'], True, True, 0)
self.cd['vbox'].show_all()
self.cd['win'].add(self.cd['vbox'])
self.cd['win'].show_all()
self.cd['win'].run()
But, if there already is a Gtk.Box in the Gtk.Dialog, how can I access it?
In another Question on Stackoverflow, there was a Dialog.get_vbox()function, but it was C/C++ and when i use bpython3 to list the functions in Gtk.Dialog, it has nothing, no get_vbox(), an also nothing else like get_vbox: no get_box()' and no get_container()`.
How can I access the Gtk.Box in Gtk.Dialog
Information:
I am using Version 3.0 of gi.repository.Gtk

Answer 1

Now I found out how to do it.
def switchfile(self, widget):
self.cd = None
self.cd = {
'win' : Gtk.Dialog(),
'entry' : Gtk.Entry(),
'btnok' : Gtk.Button.new_from_icon_name("document-open-symbolic", Gtk.IconSize.MENU),
'label' : Gtk.Label(),
'vbox' : None,
'hbox' : Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL)
}
self.cd['win'].add_buttons(
Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
Gtk.STOCK_OK, Gtk.ResponseType.OK
)
self.cd['vbox'] = self.cd['win'].get_content_area()
self.cd['entry'].set_placeholder_text('Notebook Name')
self.cd['btnok'].connect('clicked', self.switch_yes)
self.cd['hbox'].pack_start(self.cd['entry'], True, True, 0)
self.cd['hbox'].pack_start(self.cd['btnok'], True, True, 0)
self.cd['vbox'].pack_start(self.cd['label'], True, True, 0)
self.cd['vbox'].pack_start(self.cd['hbox'], True, True, 0)
self.cd['vbox'].show_all()
self.cd['win'].show_all()
self.cd['win'].run()
Important is this line:
self.cd['vbox'] = self.cd['win'].get_content_area()
I didn't know about that function, but this is how to access the Gtk.Box in Gtk.Dialog objects.