1 Terminology

     2 ===========

     3 

     4 

     5 Buffer

     6 ------

     7 

     8 Buffer is rectangular offscreen area of known size.

     9 

    10 It can be drawn on the screen or into another buffer.

    11 

    12 

    13 Widget

    14 ------

    15 

    16 Basic element of the application.

    17 

    18 * Can draw itself in given buffer on given position.