if index is equal to the line length, then position iterator before

if index is equal to the line length, then position iterator before

2001-01-04  Havoc Pennington  <hp@redhat.com>

	* gtk/gtktextlayout.c (line_display_index_to_iter): if index is
	equal to the line length, then position iterator before paragraph
	separators. Fixes crash reported by Mikael Hermansson when
	pressing left arrow from the start of a line.

	* gtk/gtktextiter.c (iter_set_from_byte_offset): Add g_error
	about byte indexes off the end
	(iter_set_from_char_offset): add g_error about char offsets
	off the end