1. Author: ngohaibac@hocdelam.org Website: www.ngohaibac.net
2. Qt Reference Documentation
3. Signals and Slots
   1. Topic
   2. A signal is emitted when a particular event occurs
      1. Emitted by Slot or other funtions
   3. A slot is a function that is called in response to a particular signal
      1. Slot is implemented by software
      2. Can emit Signal
   4. connect a signal to a slot, the slot will be called with the signal's parameters at the right time
   5. Connect
      1. QObject::connect()