if State.mouse_down then
    maxl,maxp = Text.mouse_pos(State)
  else
    maxl,maxp = State.cursor1.line,State.cursor1.pos
  end
  if Text.lt1({line=maxl, pos=maxp},
              {line=minl, pos=minp}) then
    minl,maxl = maxl,minl
    minp,maxp = maxp,minp
  end
  -- check if intervals are disjoint
  if line_index < minl then return nil,nil end
  if line_index > maxl then return nil,nil end
  if line_index == minl and bpos <= minp then return nil,nil end
  if line_index == maxl and apos >= maxp then return nil,nil end
  -- compare bounds more carefully (start inclusive, end exclusive)
  local a_ge = Text.le1({line=minl, pos=minp}, {line=line_index, pos=apos})
  local b_lt = Text.lt1({line=line_index, pos=bpos}, {line=maxl, pos=maxp})

  State.mouse_down = mouse_button
  State.mouse_down = nil
  if State.lines.current_drawing then
--?   print_and_log(('edit.mouse_press: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))