For the record, questions about libraries, like G4P or ControlP5, must go to the Contributed Library Questions. Thanks.

If you recently sent an email to me about this topic then I have responded. Just in case you are someone else or you are trying something similar then this is my answer ---

When using G4P there are 2 things that need to be considered

1. creation of the components and
2. handling of the events.

Most users will do both these inside the main sketch window and in this case when Processing runs the program it wraps up your code inside a class (same name as the skecth) then send the result to javac to compile and then to the jvm (Java virtual machine) which will create an object from this class and run it. So even though you have not explicitly created a class for your code one is created for you.

If you create you own class inside the main sketch window or in a seperate pde tab then the class will be considered an 'inner' class to the one created by Processing and this will not work. The solution is to create a seperate Java class. What follows is a very simple example (this code works I have tested it).

Create a sketch and add the following code

== Main sketch code ==============================