                 read_only             : true
             @worksheet = new (sagews.SynchronizedWorksheet)(@view_doc, opts0)
 
-        if @ext == 'ipynb2'
+        if @ext == 'ipynb' and @jupyter_classic()
             @view_doc.once 'ready', =>
                 @view_doc.element.find(".smc-jupyter-notebook-buttons").hide()
                 @show()

            @_open_file_path = @_path
        @ext = misc.filename_extension(@_path)
        if @ext == 'ipynb'
            @_path = misc.meta_file(@_path, 'jupyter2')
        if @ext == 'ipynb2'
            @_path = '.' + @_path + require('./editor_jupyter').IPYTHON_SYNCFILE_EXTENSION
        if s.head
            @_path = s.head + '/' + @_path


    set_doc: (time) =>
        if not time?
            return
        if @ext == 'ipynb' and not @jupyter_classic()
            @view_doc.set_version(time)
        else
            val = @syncstring.version(time).to_str()
            switch @ext
                when 'ipynb'  # must be classic since not handled above
                    @view_doc.dom.set(val)
                when 'tasks'
                    @view_doc.set_value(val)
