The examples are explained in the following sections.

Example 1

The screen is the parent of the Container, and it
forces the Container to be exactly the same size as the screen.

So the Container fills the screen and paints it red.

Example 2

The red Container wants to be 100 × 100,
but it can’t, because the screen forces it to be
exactly the same size as the screen.

So the Container fills the screen.

Example 3

The screen forces the Center to be exactly the same size
as the screen, so the Center fills the screen.

The Center tells the Container that it can be any size it
wants, but not bigger than the screen. Now the Container
can indeed be 100 × 100.

Example 4

This is different from the previous example in that it uses
Align instead of Center.