Skip noticed that the document talks about "setting PythonLauncher as the
default application" but doesn't give a clue on how to do this. Refer to
Apple Help.
diff --git a/Mac/OSX/Extras.ReadMe.txt b/Mac/OSX/Extras.ReadMe.txt
index c41e89c..3ab4568 100644
--- a/Mac/OSX/Extras.ReadMe.txt
+++ b/Mac/OSX/Extras.ReadMe.txt
@@ -7,6 +7,8 @@
Some examples can be run from within the PythonIDE, but many will require
that you start them from the command line or with PythonLauncher. In the
latter case, you can supply any needed command line arguments by holding
-the "alt" key while dragging the script to PythonLauncher (or while
-double-clicking the script, if PythonLauncher is set as the default application
-to open Python scripts with).
+the "alt" key while dragging the script to PythonLauncher, or while
+double-clicking the script if PythonLauncher is set as the default application
+to open Python scripts with. See "Changing the application that opens a file"
+in Mac Help for information on making PythonLauncher the default application.
+