2000-09-23  Almer S. Tigelaar  <almer1@dds.nl>

	* src/stf-parse.c, src/stf-parse.h:
	(stf_parse_is_valid_data): return invalid character
	or NULL if the data is valid.

	* src/clipboard.c:
	(stf_read_workbook): Adjust to cope with the new
	stf_parse_is_valid_data.

	* src/stf.c:
	(x_selection_to_cell_region): Idem.