SetRepRule

This function sets the low-level graphics pixel replacement rule. The valid replacement rules are

      REP_FORCE       0.  
      REP_AND         1.  
      REP_OR          2.  
      REP_XOR         3.  
      REP_NOTFORCE    4. 
      REP_NOTAND      5.  
      REP_NOTOR       6.  
      REP_NOTXOR      7. 
      REP_BITBLT      8.