Controlling close events in SAP Business One Screen Painter

You can make use of SP_TransactionNotification, which is one of the most common way of receiving notification of data-driven events. With the use of SP_TransactionNotification, you can edit error code returned by Transaction notification, and also prevent transaction to committed.

This shows how to prevent a purchase order from adding when the base document is not provided. You can make use of SBO_SP_TransactionNotification for Screen Painter forms in SBO to avoid null values.