Added a note that multiple threads breaks command-.
diff --git a/Mac/Relnotes b/Mac/Relnotes
index 006c359..a08691e 100644
--- a/Mac/Relnotes
+++ b/Mac/Relnotes
@@ -45,3 +45,5 @@
 
 - The IDE and Tkinter do not work together. Run tkinter programs under PythonInterpreter.
 - Aliases do not work in sys.path entries.
+- Once you have used multiple threads you cannot raise KeyboardInterrupt anymore:
+  typing command-. will immedeately exit the interpreter.