The normal way is to define some symbolic constants and write a method to replace the symbolic constants with real functions. Wbuild does this automatically, so that all methods are always properly inherited. In that case you are responsible for implementating inheritance yourself. This calls a function that wbuild has generated. They are copied unchanged to the produced C code.
Subclasses provide buttons of other, more specialized types.
There are no new or redefined methods. In contrast to its superclass XfwfLabel, a button usually takes part in keyboard traversal. The methods for the Core and Composite classes are declared in the wbuild.cfg configuration file. To be able to override these methods, you'll need to know how they are declared. Here is a list, with some remarks.