The layout sample demonstrates the two different layout systems offered by wxWidgets. When starting the program, you will see a frame with some controls and some graphics. The controls will change their size whenever you resize the entire frame and the exact behaviour of the size changes is determined using the wxLayoutConstraints class. See also the overview and the wxIndividualLayoutConstraint class for further information.
The menu in this sample offers two more tests, one showing how to use a wxBoxSizer in a simple dialog and the other one showing how to use sizers in connection with a wxNotebook class. See also wxSizer.