lec = LibStub:GetLibrary("LibEventController-1.0");
function chat_msg_whisper(controller, event, ...)
   -- controller:Suspend() -- don't deliver event just yet,
   -- suspend is ideal to check credetials (who look up) before delivery.
   -- controller:Release() -- release a suspended event
   -- controller:Block() -- block event from ever being delivered.
   -- controller:BlockFrom(frame[,frame2, frame3...])
   -- controller:Allow() -- same as doing nothing, deliver as normal

   -- controller.arg[1...]
   -- controller.frames[1...] -- list of frames waiting for event.
end
lec:RegisterEventController("CHAT_MSG_WHISPER", chat_msg_whisper);