# File lib_wpm/wpm.rb, line 1717
    def parent_page
      component = @parent_component
      loop do
        case (component)
        when Page
          return component
        when NilClass
          raise WidgetError, "not found a page widget upper #{widget_id.inspect}"
        end
        component = component.parent_component
      end

      raise 'internal error'
    end