This example program shows how to use

 - different types of buttons
 - different types of groupboxes

The buttons which are used are radiobuttons, checkboxes (also tristate checkboxes), 
normal pusbuttons and toggleable pushbuttons.
These buttons are seperated in four groups using groupboxes. The example shows how
to make a buttongroup totally exclusive (only one button can be checked), exclusive
for radiobuttons only or non-exclusive. Also it is demonstrated how buttons (and
other widgets too!) can be laid out in rows and columns in a groupbox.

Important parts of the source code are documented as well to make it easy to understand.
