XYGraph__PlotDataXor (ul_pbar_graphics)

 *  Synopsis:
 *    #include <ul_pbar_graphics:xygraph.h>
 *
 *    TXYGraph__Result XYGraph__PlotDataXor( int dataCount,
 *					     const TXYGraph__Data *xData,
 *					     const TXYGraph__Data *yData,
 *					     int color )
 *
 *  Function intent:
 *    XYGraph__PlotDataXor() plots a specified number of data points from
 *    individual X and Y data arrays with a specified display color in the
 *    WN_XOR drawing mode so that another subsequent identical call will
 *    erase the plot.
 *  Function parameters:
 *    int		dataCount	Number of points to erase
 *    TXYGraph__Data	xData		X data array
 *    TXYGraph__Data	yData		Y data array
 *    int		color		Original Color of the plot
 *  Function return value:
 *    CBS_OK		success
 *    CBS_NOSETUP	XYGraph__DisplayGraph() not yet called
 *    else 		wn_xxx() function error occured