blendMode() should be a warning, not fatal

core/todo.txt

@@ -1,4 +1,5 @@
 0265 (3.3.8 or 3.4)
+X change lack of blendMode() to a warning rather than an error in PDF
 
 
 gohai
@@ -15,6 +16,9 @@ X   https://github.com/processing/processing/pull/5202
 _   need to make this work behind the scenes instead
 _   create icon.png or have an 'icons' folder with multiple sizes
 
+_ Implement blendMode() for PDF
+_   https://github.com/processing/processing/issues/5438
+
 _ many shift- keys not working properly in FX2D (added a test sketch)
 _   https://github.com/processing/processing/issues/5317
 

java/libraries/pdf/src/processing/pdf/PGraphicsPDF.java

@@ -1,7 +1,8 @@
 /*
   Part of the Processing project - http://processing.org
 
-  Copyright (c) 2005-11 Ben Fry and Casey Reas
+  Copyright (c) 2005-12 Ben Fry and Casey Reas
+  Copyright (c) 2012-18 The Processing Foundation
 
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
@@ -551,8 +552,8 @@ public class PGraphicsPDF extends PGraphicsJava2D {
   //
 
   protected void blendModeImpl() {
-    if (blendMode != BLEND) {
-      nope("blendMode");
+    if (blendMode != REPLACE && blendMode != BLEND) {
+      showMissingWarning("blendMode");
     }
   }