JDAPI has full support for Forms object subclassing. There are three ways to
subclass using JDAPI:
The first two are similar to the Form Builder's functionality. The third is more complex and requires a good knowledge of the Forms model. As the previous example indicated, it is possible to subclass objects from an appropriate source directly on construction. There are also a number of common methods to enable subclassing (or re-subclassing) of preexisting objects, and for modifying the subclassing on individual properties of Forms objects. Finally, the low-level subclassing settings can be manipulated directly. This third approach is not available in the Form Builder.
If the subclassed source object is located in a different module to the target object, then the source module must be saved before you can subclass from it.