Callback Function

• The callback function is a normal callback function for that widget
• It makes a dynamic call to Java code for the peer object by

  JAVA_UPCALL((EE(), (void *)client_data, 
              "method", "(<arg-types>)V",
              args...))
  

• arg-types is a list of types such as BBIC
• Each arg type is defined in src/share/java/include/signature.h
  • I - integer
  • B - byte
  • C - char, etc