>I have a form using several (many) instances of the textbox class. I have now created my own subclass of the textbox. I would like to automate the process of changing the class names. Is this possible? If so, how exactly do I do this? TIA.

After making a zipfile, for example, backup, you can something like:

USE MyForm.SCX 
COPY TO MyForm_Save.SCX && redundant backups can never be a bad thing
REPLACE FOR BASECLASS = 'textbox' class with 'MyTextBox', classloc with "MyClassLib.vcx"
USE