--- a/AbstractBackground.st	Fri Feb 10 11:20:37 2017 +0100
+++ b/AbstractBackground.st	Fri Feb 10 11:22:19 2017 +0100
@@ -1,5 +1,3 @@
-"{ Encoding: utf8 }"
-
 "
  COPYRIGHT (c) 2009 by eXept Software AG
               All Rights Reserved
@@ -66,6 +64,16 @@
 "
 ! !
 
+!AbstractBackground class methodsFor:'queries'!
+
+isAbstract
+    "Return if this class is an abstract class.
+     True is returned here for myself only; false for subclasses.
+     Abstract subclasses must redefine this again."
+
+    ^ self == AbstractBackground.
+! !
+
 !AbstractBackground methodsFor:'drawing'!
 
 fillRectangleX:x y:y width:w height:h in:aView