-- selection remains empty
  check_nil(Editor_state.selection1.line, 'selection is empty to avoid perturbing future edits')
end
function test_draw_text()
  check_eq(Editor_state.cursor1.line, 1, 'cursor')
  -- selection remains empty
  check_nil(Editor_state.selection1.line, 'selection is empty to avoid perturbing future edits')
end
function test_click_below_all_lines()
  -- display one line
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  -- click below first line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+50, 1)
  -- cursor doesn't move
  check_eq(Editor_state.cursor1.line, 1, 'cursor')
  Editor_state.selection1 = {}
  -- click on the empty line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  Editor_state.selection1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  Editor_state.selection1 = {}
  -- click to the left of the line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left-4,Editor_state.top+5, 1)
  -- cursor moves to start of line

  State.old_cursor1, State.old_selection1, State.mousepress_shift = nil
  if eq(State.cursor1, State.selection1) then
    State.selection1 = {}
  end
end
function edit.mouse_wheel_move(State, dx,dy)
  if dy > 0 then
    State.cursor1 = {line=State.screen_top1.line, pos=State.screen_top1.pos}
  end
end
function edit.clean_up_mouse_press(State)
  if State.mousepress_shift then
    if State.old_selection1.line == nil then
      State.selection1 = State.old_cursor1
    else
      State.selection1 = State.old_selection1
    end
  end
    -- still here? mouse release is below all screen lines
    State.cursor1.line, State.cursor1.pos = State.screen_bottom1.line, Text.pos_at_end_of_screen_line(State, State.screen_bottom1)
    edit.clean_up_mouse_press(State)
--?     print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d'):format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
          edit.clean_up_mouse_press(State)
          return
        end
      end
    end
    if y < State.top then
      State.cursor1 = {line=State.screen_top1.line, pos=State.screen_top1.pos}
      edit.clean_up_mouse_press(State)
      return
    end
    for line_index,line in ipairs(State.lines) do
      if line.mode == 'text' then
        if Text.in_line(State, line_index, x,y) then
  -- still here? mouse press is below all screen lines
  State.old_cursor1 = State.cursor1
  State.old_selection1 = State.selection1
  State.mousepress_shift = App.shift_down()
  State.selection1 = {
      line=State.screen_bottom1.line,
      pos=Text.pos_at_end_of_screen_line(State, State.screen_bottom1),
  }