column.i4.v = window_physical_column_c(window_id.i2.v,

	This routine allows the programmer to calculate the proper column
	for window I/O in a horizontally scrolling window.  It converts
	from the caller's virtual column number in memory to the corresponding
	physical window I/O column.

	window_id	ID of desired window
	virtual_column	virtual column number
	[start]		first virtual column number (default is 1)
	[scroll_offset]	window scroll offset
			(CLIB_DEFAULT_ARG -> use window's current scroll offset,
			 <0 -> use window's current scroll offset,
			 otherwise -> use passed scroll offset)
			(default is CLIB_DEFAULT_ARG)

	This function returns status values as follows:

	CBS_INVARG		invalid window ID or invalid virtual column
	CBS_NO_WINDOW		window doesn't exist
	otherwise		corresponding physical window column

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	window_virtual_column_c, window_hscroll_c, window_tvm(_c),
	window_tvmx(_c), window_entry_to_row_c, window_row_to_entry_c,
	window_current_row_c, window_scroll(_c), window_is_in_scroll_buffer_c,
	window_read_text_c, window_read_color_text_c, window_display_value(_c)

	C/C++ usage:

	short	window_id;
	int	column;
	int	virtual_column = 5;
	int	start = 1;
	int	scroll_offset = 0;

	column = window_physical_column_c(window_id,virtual_column,