+ Notice that you need to call DestroyClippingRegion() if you want to set
+ the clipping region exactly to the region specified.
+
+ Also note that if the clipping region is empty, any previously set
+ clipping region is destroyed, i.e. it is equivalent to calling
+ DestroyClippingRegion(), and not to clipping out all drawing on the DC
+ as might be expected.
+