             save
 
     set_cell_output: (id, output, save=true) =>
-        @_checked_set
+        @_set
             type   : 'cell'
             id     : id
             output : output,

        @setState(md_edit_ids : md_edit_ids.delete(id))

    change_cell_to_heading: (id, n=1) =>
        try
            @set_md_cell_editing(id)
        catch ex
            if ex is CellWriteProtectedException
                @show_edit_protection_error()
                return
            else
                throw ex
        @set_cell_type(id, 'markdown')
        input = misc.lstrip(@_get_cell_input(id))
        i = 0

            @move_cursor_before(selected[0])
        not_deletable = 0
        for id in selected
            if not @store.is_cell_deletable(id)
                not_deletable += 1
            else
                @_delete({type:'cell', id:id}, false)
        if sync
            @_sync()
        if not_deletable > 0
