--- a/GraphicsContext.st	Fri Feb 17 16:04:32 2017 +0100
+++ b/GraphicsContext.st	Fri Feb 17 17:29:00 2017 +0100
@@ -850,9 +850,14 @@
 !
 
 function:aFunctionSymbol
-    "set the drawing function"
+    "set the (bitblt) drawing function.
+     The argument is one of:
+        #and, #or, #copy
+    "
 
     ^ self subclassResponsibility
+
+    "Modified (comment): / 17-02-2017 / 16:44:24 / cg"
 !
 
 graphicsContext