assert(false, ('Text.offset(%d) called on a string of length %d (byte size %d); this is likely a failure to handle utf8\n\n^%s$\n'):format(pos1, utf8.len(s), #s, s))
  end

  edit.draw(Editor_state)
  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,5, 1)
  -- selection is at screen top
  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
  check_eq(Editor_state.selection1.line, 2, 'selection:line')
  check_eq(Editor_state.selection1.pos, 3, 'selection:pos')
end
function test_select_text_using_mouse_starting_below_text()
  -- I'd like to test what happens when a mouse click is below some page of
  -- text, potentially even in the middle of a line.
  -- However, it's brittle to set up a text line boundary just right.
  -- So I'm going to just check things below the bottom of the final line of
  -- text when it's in the middle of the screen.
  -- final screen line ends in the middle of screen
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abcde'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'ab', 'baseline:screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'cde', 'baseline:screen:2')
  -- press mouse above first line of text
  edit.run_after_mouse_press(Editor_state, 5,App.screen.height-5, 1)
  -- selection is past bottom-most text in screen
  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
  check_eq(Editor_state.selection1.line, 1, 'selection:line')
  check_eq(Editor_state.selection1.pos, 6, 'selection:pos')
end

  if mouse_press_consumed_by_any_button(State, x,y, mouse_button) then
    -- press on a button and it returned 'true' to short-circuit
    return
  end