message: tfdbg: Curses CLI: Fill line-end whitespace with default color pair
  to prevent spurious color pairs from appearing in certain text
  terminal environments.
  RELNOTES: Bug fix: tfdbg curses CLI: fix spurious background colors in some text terminals.
diff: @@ -1185,6 +1185,22 @@ class CursesUI(base_ui.BaseUI):
  self._main_menu = None
  self._main_menu_pad = None
  + def _pad_line_end_with_whitespace(self, pad, row, line_end_x):
  + """Pad the whitespace at the end of a line with the default color pair.
  +
  + Prevents spurious color pairs from appearing at the end of the lines in
  + certain text terimnals.
  +
  + Args:
  + pad: The curses pad object to operate on.
  + row: (`int`) row index.
  + line_end_x: (`int`) column index of the end of the line (beginning of
  + the whitespace).
  + """
  + if line_end_x < self._max_x - 2:
  + pad.addstr(row, line_end_x, " " * (self._max_x - 3 - line_end_x),
  + self._default_color_pair)
  +
  def _screen_add_line_to_output_pad(self, pad, row, txt, color_segments=None):
  """Render a line in a text pad.
  @@ -1208,6 +1224,7 @@ class CursesUI(base_ui.BaseUI):
  if not color_segments:
  pad.addstr(row, 0, txt, self._default_color_pair)
  + self._pad_line_end_with_whitespace(pad, row, len(txt))
  return
  if not isinstance(color_segments, list):
  @@ -1248,6 +1265,8 @@ class CursesUI(base_ui.BaseUI):
  for segment, color_pair in zip(all_segments, all_color_pairs):
  if segment[1] < self._max_x:
  pad.addstr(row, segment[0], txt[segment[0]:segment[1]], color_pair)
  + if all_segments:
  + self._pad_line_end_with_whitespace(pad, row, all_segments[-1][1])
  def _screen_scroll_output_pad(self, pad, viewport_top, viewport_left,
  screen_location_top, screen_location_left,
  