def _emit_via(parent, options = {}, &block)
      _emit(options.merge(:parent  => parent,
                            :output  => parent.output,
                            :helpers => parent.helpers), &block)
    end
def _emit_via(parent, options = {}, &block)
      _emit(options.merge(:parent  => parent,
                            :output  => parent.output,
                            :helpers => parent.helpers), &block)
    end
same as _emit, but using a parent widget's output stream and helpers