Button
  
  The Button widget in SWT incorporates different types of buttons
  that can be selected by specifying style flags.
  
  
    - PUSH
- 
      Normal push buttons. They have no state.
      When the buttons is pressed, a selection event is fired.
    
- TOGGLE
- 
      Toggle buttons look like push buttons but they maintain a selection state.
      Once pressed they stay selected until they are pressed again.
      A selection event is fired on selection and deselection.
    
- CHECK
- 
      Check buttons are semantically equivalent to toggle buttons.
      They also maintain a selection state but this state is displayed as a checkbox.
    
- RADIO
- 
      Radio buttons are used to choose between different options.
      A radio button can only be deselected by selecting another radio button
      within the same composite.