Not really enough info for me to help you. What I would suggest is that you either create a patch against SVN HEAD and paste it into a code block here; or post the affected files (in a code block here). Try to limit your changes to just enough to show what you are working on. Post mock-ups of GUI changes–it makes it easier to see what you are doing. Try to tell us more about what you are trying to do with the button and handler.
I think adding an event handler to a button will require some knowledge of wxWidgets.