2001-04-27  Chema Celorio  <chema@celorio.com>

	* src/sheet-object.h: add the header for clone_sheet

	* src/sheet-object.c (sheet_object_clone): implement
	(sheet_object_clone_sheet): implemnt.

	* src/sheet-object-widget.c (SOW_MAKE_TYPE): add read_xml, write_xml
	and clone methods to macro
	(sheet_object_widget_clone): implement.
	Implement for X in label, frame, button, checkbox
	(sheet_widget_x_construct_with_label):
	(sheet_widget_x_destroy):
	(sheet_widget_x_clone):
	(sheet_widget_x_write_xml):
	(sheet_widget_x_read_xml):

	(sheet_object_widget_register): implement

	* src/sheet-object-impl.h: add the clone method

	* src/sheet-object-graphic.c (sheet_object_graphic_clone): implement.
	(sheet_object_filled_clone): implement.

	* src/sheet-object-cell-comment.c (cell_comment_clone): implement