
my_pack=fltk.Fl_Pack(x,y,width,height) -- create the pack
my_pack:type(fltk.FL_HORIZONTAL) -- if you want a horizonal pack
fltk:Fl_End() -- required to end the pack group
my_pack:add(widget) -- add a widget to the pack

Fl_Pack is a special class of Fl_Group that allows widgets
to be neatly lined up within it. It dynamically expands
vertically (or horizontally if type is FL_HORIZONTAL)
as more widgets are added. This behavior allows the
contained widgets to be created without specifying
their x and y positions, and the pack itself to be
created without specifying its height (or width if
type is FL_HORIZONTAL).

Fl_Pack works well when placed within Fl_Scroll,
as seen in the fonts-system.lua example. This allows
an arbitrary number of widgets to be added to the
group while keeping the group itself a limited size.
When doing this it is a good idea to make the width
of Fl_Scroll slightly larger than the pack width to
allow room for the scrollbar.
