                         <ButtonGroup>
                             {@render_timetravel_button()}
                             {@render_bottom_button()}
-                            {#Disabled -- see https://github.com/sagemathinc/smc/issues/794}
-                            {#@render_preview_button_on() if @state.preview_button}
-                            {#@render_preview_button_off() if not @state.preview_button}
                         </ButtonGroup>
                     </Col>
                 </Row>

        @props.actions.set_input('')

    button_off_click: ->
        @props.actions.set_preview_button(true)
        @props.actions.set_is_preview(false)
        ReactDOM.findDOMNode(@refs.input.refs.input).focus()

    button_on_click: ->
        @props.actions.set_preview_button(false)
        @props.actions.set_is_preview(true)
        ReactDOM.findDOMNode(@refs.input.refs.input).focus()
        if @is_at_bottom()

            offset         : rtypes.number
            saved_mesg     : rtypes.string
            is_preview     : rtypes.bool
        users :
            user_map : rtypes.immutable
        account :
