adding raster op hook to graphics context

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43761 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dcgraph.h

@@ -171,6 +171,7 @@ protected:
 
 protected:
     // scaling variables
+    bool m_logicalFunctionSupported;
     double       m_mm_to_pix_x, m_mm_to_pix_y;
     wxGraphicsMatrix m_matrixOriginal;
     wxGraphicsMatrix m_matrixCurrent;