{{{  comments
; simulate the tds-operations TOP and BOTTOM, which jump to top and bottom
; of currently OPENED fold.
; -----------------------------------------------------------------------------
; if tag SCR-OFF is set, the go will be done without display
}}}
@if-using not(MT-FOLD)
  @use (MT-FOLD)
  {{{  top
  ( deffun mtool-top
     ( @if-using (SCR-OFF)
         screen-off
       @fi
       if test-end-fold ( previous-line ) fi
       while and(not(test-begin-fold),not(test-top))
        ( if test-end-fold ( mtool-top ) fi
           previous-line
        )
       @if-using (SCR-OFF)
         screen-on
         redraw-display
       @fi
     )
  )
  }}}
  {{{  bot
  ( deffun mtool-bot
     ( @if-using (SCR-OFF)
         screen-off
       @fi
       if test-begin-fold (next-line) fi
       while and(not(test-end-fold),not(test-bottom))
        ( if test-begin-fold ( mtool-bot ) fi
          next-line
        )
       @if-using (SCR-OFF)
         screen-on
         redraw-display
       @fi
     )
  )
  }}}
@fi
