The cursor border was not being resized when rows/cols were hidden.
Cell contents were not being re-rendered/sized when the format was
    cleared.

2000-05-19  Jody Goldberg <jgoldberg@home.com>

	* src/sheet.c (sheet_update) : Update cursor positions when visibility
	  changes.
	(sheet_clear_region) : When clearing formats we need to update the
	  spans and sizes of the contents.
	(sheet_update_cursor_pos) : New function.
	(sheet_row_col_visible) : changing the status of a row/col changes visibility.

	* src/sheet-view.c (sheet_view_update_cursor_pos) : New function split
	  out from sheet_view_set_zoom_factor.
	(sheet_view_set_zoom_factor) : Use sheet_view_update_cursor_pos.