
Various shapes and styles for your buttons.

Although there is a kind of order in the table of buttons
in the script, Lua has a habit of making up its own order
of traversing non-numeric tables that, while it probably
has some logic behind it, results in a seemingly random
order in the display of its contents.

The "UP" state of these box types apparently causes a
button to also inherit the "DOWN" state of the same
box type. You can see this when clicking on the example
buttons; the up state will change to down when clicked,
but the buttons already in a down state do not change.

IMPORTANT NOTES:

One or more of the following functions must run before the
associated boxtype(s) can be applied to an arbitrary widget:

fltk.fl_define_FL_PLASTIC_UP_BOX()
fltk.fl_define_FL_OVAL_BOX()
fltk.fl_define_FL_RFLAT_BOX()
fltk.fl_define_FL_SHADOW_BOX()
fltk.fl_define_FL_ROUND_UP_BOX()
fltk.fl_define_FL_RSHADOW_BOX()
fltk.fl_define_FL_DIAMOND_BOX()
fltk.fl_define_FL_ROUNDED_BOX()
fltk.fl_define_FL_GTK_UP_BOX()

Boxtypes not associated with the above constants, such as
FL_THIN_UP_BOX or FL_BORDER_FRAME, do not need a special
function to define them.  Using one of the built-in FLTK
schemes apparently runs the needed function for that scheme,
saving you from needing to run it yourself.

