It's important to note that the Language Selector list will change based on the element being edited. The Designer client will only display languages that are applicable for the selected design element.
Be careful when changing the programming language. Changing the language after you've added code to a particular element can result in the code being deleted! If the object already contains code, Designer will display a warning message that gives you the option to continue or cancel the change.
An Introduction to the Lotus Domino Tool Suite
Getting Started with Designer
Navigating the Domino Designer Workspace
Domino Design Elements
An Introduction to Formula Language
An Introduction to LotusScript
Fundamentals of a Notes Application
Reference Library Applications
Design Enhancements Using LotusScript
Design Enhancements Using Formula Language
Miscellaneous Enhancements and Tips for Domino Databases
Application Deployment and Maintenance
Appendix A. Online Project Files and Sample Applications
Appendix B. IBM® Lotus® Notes® and Domino®Whats Next?