The basic idea behind a box sizer is that windows will most often be laid out in rather simple basic geometry, typically in a row or a column or several hierarchies of either.
For more information, please see Programming with wxBoxSizer.
wxSizer, Sizer overview
Constructor for a wxBoxSizer. orient may be either of wxVERTICAL or wxHORIZONTAL for creating either a column sizer or a row sizer.
Implements the calculation of a box sizer's dimensions and then sets the size of its its children (calling wxWindow::SetSize if the child is a window). It is used internally only and must not be called by the user. Documented for information.
Implements the calculation of a box sizer's minimal. It is used internally only and must not be called by the user. Documented for information.
Returns the orientation of the box sizer, either wxVERTICAL or wxHORIZONTAL.