There should be a small button in the center of the screen.
add() buttons (and other components)
to a content pane,
a layout manager automatically
decides what size they will be and where they will go.
This is convenient,
because you can add components
without worrying about the details.
manager is like a little artist inside the computer.
You say what components you want and
the layout manager lays them out in the picture.
The layout manager sometimes makes odd choices. However, there are several kinds of layout managers. Each layout manager has a different style of positioning components. Usually there is a layout manager that will do the job you want. If you don't specify otherwise, a default layout manager is used.