OScope__ClearAnnotation (ul_pbar_graphics)

 *  Synopsis:
 *    #include <ul_pbar_graphics:oscope.h>
 *
 *    TOScope__Result OScope__ClearAnnotation( void )
 *
 *  Function intent:
 *    OScope__ClearScreen() clears the annotation window.
 *  Function parameters:
 *    none
 *  Function return value:
 *    CBS_OK            success
 *    CBS_NOSETUP       OScope__EnableAnnotation() has not been called
 *    else              wn_xxx() function error occured