tvbox

	TVBOX(col1.i4.r, row1.i4.r, col2.i4.r, row2.i4.r, color.i4.r
	      [,style.i4.r])

	tvbox_c(col1.i4.v, row1.i4.v, col2.i4.v, row2.i4.v, color.i4.v
		[,style.i4.v])

	Draw a rectangle on the color TV.  ('row1', 'col1') and 
	('row2', 'col2') specify diagonal corners.

	col1, row1	upper left hand corner of box
	col2, row2	lower right hand corner of box
	color		color of box (constants are in cnsparam)
	[style]		(LINE_THIN -> thin lined box (default),
			 LINE_THICK -> thick lined box)

	This function requires the following include files:

	cnsparam_h, cbslib_h

	Related functions:

	window_box_c, window_rectangle_c, window_hline_c, window_vline_c,
	wtvbox_c, tvhlin(_c), tvvlin(_c)