widget: CalculatorPopup
GtkWindow(): title=None, hidden
  GtkFrame():
    GtkAlignment():
      GtkVBox():
        GtkLabel(_main_label, expand=True, fill=True):
        ProxyEntry(_entry, expand=True, fill=True): ''
        GtkHBox(expand=True, fill=True):
          GtkLabel(_label, expand=True, fill=True):
          GtkImage(_warning): hidden
