function test_pageup()
  io.write('\ntest_pageup')
  App.screen.init{width=120, height=45}
  Lines = load_array{'abc', 'def', 'ghi'}
  Line_width = App.screen.width
  Cursor1 = {line=2, pos=1}
  Screen_top1 = {line=2, pos=1}
  Screen_bottom1 = {}
  Zoom = 1
  local screen_top_margin = 15  -- pixels
  local line_height = math.floor(15*Zoom)  -- pixels
  -- initially the last two lines are displayed
  App.draw()
  local y = screen_top_margin
  App.screen.check(y, 'def', 'F - test_pageup/baseline/screen:1')
  y = y + line_height
  App.screen.check(y, 'ghi', 'F - test_pageup/baseline/screen:2')
  -- after pageup the cursor goes to first line
  App.run_after_keychord('pageup')
  check_eq(Screen_top1.line, 1, 'F - test_pageup/screen_top')
  check_eq(Cursor1.line, 1, 'F - test_pageup/cursor')
  y = screen_top_margin
  App.screen.check(y, 'abc', 'F - test_pageup/screen:1')
  y = y + line_height
  App.screen.check(y, 'def', 'F - test_pageup/screen:2')
end
function test_pageup_scrolls_up_by_screen_line()
  io.write('\ntest_pageup_scrolls_up_by_screen_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=25+30, height=60}
  Lines = load_array{'abc def', 'ghi', 'jkl', 'mno'}
  Line_width = App.screen.width
  Cursor1 = {line=2, pos=1}
  Screen_top1 = {line=2, pos=1}
  Screen_bottom1 = {}
  Zoom = 1
  local screen_top_margin = 15  -- pixels
  local line_height = math.floor(15*Zoom)  -- pixels
  App.draw()
  local y = screen_top_margin
  App.screen.check(y, 'ghi', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:1')
  y = y + line_height
  App.screen.check(y, 'jkl', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:2')
  y = y + line_height
  App.screen.check(y, 'mno', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the page-up key the screen scrolls up to top
  App.run_after_keychord('pageup')
  check_eq(Screen_top1.line, 1, 'F - test_pageup_scrolls_up_by_screen_line/screen_top')
  check_eq(Cursor1.line, 1, 'F - test_pageup_scrolls_up_by_screen_line/cursor:line')
  check_eq(Cursor1.pos, 1, 'F - test_pageup_scrolls_up_by_screen_line/cursor:pos')
  y = screen_top_margin
  App.screen.check(y, 'abc ', 'F - test_pageup_scrolls_up_by_screen_line/screen:1')
  y = y + line_height
  App.screen.check(y, 'def', 'F - test_pageup_scrolls_up_by_screen_line/screen:2')
  y = y + line_height
  App.screen.check(y, 'ghi', 'F - test_pageup_scrolls_up_by_screen_line/screen:3')
end
function test_pageup_scrolls_up_from_middle_screen_line()
  io.write('\ntest_pageup_scrolls_up_from_middle_screen_line')
  -- display a few lines starting from the middle of a line (Cursor1.pos > 1)
  App.screen.init{width=25+30, height=60}
  Lines = load_array{'abc def', 'ghi jkl', 'mno'}
  Line_width = App.screen.width
  Cursor1 = {line=2, pos=5}
  Screen_top1 = {line=2, pos=5}
  Screen_bottom1 = {}
  Zoom = 1
  local screen_top_margin = 15  -- pixels
  local line_height = math.floor(15*Zoom)  -- pixels
  App.draw()
  local y = screen_top_margin
  App.screen.check(y, 'jkl', 'F - test_pageup_scrolls_up_from_middle_screen_line/baseline/screen:2')
  y = y + line_height
  App.screen.check(y, 'mno', 'F - test_pageup_scrolls_up_from_middle_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the page-up key the screen scrolls up to top
  App.run_after_keychord('pageup')
  check_eq(Screen_top1.line, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/screen_top')
  check_eq(Cursor1.line, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/cursor:line')
  check_eq(Cursor1.pos, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/cursor:pos')
  y = screen_top_margin
  App.screen.check(y, 'abc ', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:1')
  y = y + line_height
  App.screen.check(y, 'def', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:2')
  y = y + line_height
  App.screen.check(y, 'ghi ', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:3')
end

--? App.screen.width = 120
--? App.screen.height = 200
--? love.window.setMode(App.screen.width, App.screen.height)

--? Line_width = 100

    local y = App.screen.height
    while y >= 0 do
      if Screen_top1.line == 1 then break end
      y = y - math.floor(15*Zoom)
      if Lines[Screen_top1.line].mode == 'drawing' then
        y = y - Drawing.pixels(Lines[Screen_top1.line].h)

    local top2 = Text.to2(Screen_top1)
--?     print(App.screen.height)
    local y = App.screen.height - math.floor(15*Zoom)
    while y >= 15 do
--?       print(y, top2.line)
      if Screen_top1.line == 1 and Screen_top1.pos == 1 then break end
      if Lines[Screen_top1.line].mode == 'text' then
        y = y - math.floor(15*Zoom)
      elseif Lines[Screen_top1.line].mode == 'drawing' then
        y = y - 20 - Drawing.pixels(Lines[Screen_top1.line].h)

      Screen_top1.line = Screen_top1.line - 1

      top2 = Text.previous_screen_line(top2)

    if Cursor1.line ~= Screen_top1.line then
      Cursor1.pos = 1
    end

    Screen_top1 = Text.to1(top2)

    Cursor1.pos = Screen_top1.pos

--?     print(Cursor1.line, Cursor1.pos, Screen_top1.line, Screen_top1.pos)