code: def form_invalid(self, form, forms, open_tabs, position_form_default):
          
          # return self.render_to_response( self.get_context_data( form = form, forms = forms ) )
          return self.render_to_response(self.get_context_data(form=form, forms=forms, open_tabs=open_tabs, position_form_default=position_form_default))
docs: Called if a form is invalid. Re-renders the context data with the data-filled forms and errors.