This is the same as Fl_Window. However, it is possible that
some implementations will provide double-buffered windows by default.
This subclass can be used to force single-buffering. This may be
useful for modifying existing programs that use incremental update, or
for some types of image data, such as a movie flipbook.
Creates a new Fl_Single_Window widget using the given
position, size, and label (title) string.
Destroys the window and all child widgets.