--- a/AbstractBackgroundJob.st	Fri Feb 10 11:17:32 2017 +0100
+++ b/AbstractBackgroundJob.st	Fri Feb 10 11:22:15 2017 +0100
@@ -140,6 +140,16 @@
     "Created: / 28-04-2011 / 20:30:03 / Jan Vrany <jan.vrany@fit.cvut.cz>"
 ! !
 
+!AbstractBackgroundJob 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 == AbstractBackgroundJob.
+! !
+
 !AbstractBackgroundJob methodsFor:'accessing'!
 
 initiatingThread