=for comment based on iup-3.5 - http://www.tecgraf.puc-rio.br/iup/en/elem/iupspin.html
=head1 NAME
IUP::Spin - [GUI element] vertical box containing 2 buttons for incrementing/decrementing values
=head1 DESCRIPTION
This functions will create a control set with a vertical box containing
two buttons, one with an up arrow and the other with a down arrow, to
be used to increment and decrement values.
Unlike the SPIN attribute of the L<IUP::Text|IUP::Text> element, the L<IUP::Spin|IUP::Spin>
element can NOT automatically increment the value and it is NOT
inserted inside the L<IUP::Text|IUP::Text> area.
=begin HTML
<p><img src="http://kmx.github.io/perl-iup/img-3.9/elem/iupspin.png"></p>
=end HTML
=head1 USAGE
=head2 CREATION - new() method
L<IUP::Spin|IUP::Spin> is based on L<IUP::Vbox|IUP::Vbox>, and contains two L<IUP::Button|IUP::Button>.
$spin = IUP::Spin->new();
B<Returns:> the identifier of the created element, or C<undef> if an error occurs.
NOTE: You can pass to C<new()> other C<ATTRIBUTE=E<gt>'value'> or C<CALLBACKNAME=E<gt>\&func> pairs relevant
to this element - see L<IUP::Manual::02_Elements|IUP::Manual::02_Elements/"new()">.
=head2 CALLBACKS
For more info about concept of callbacks (setting callback handlers etc.)
see L<IUP::Manual::04_Callbacks|IUP::Manual::04_Callbacks>. Callbacks specific to this element:
=over
=item B<SPIN_CB>
Called each time the user clicks in the buttons. It will
increment 1 and decrement -1 by default. Holding the Shift key will set
a factor of 2, holding Ctrl a factor of 10, and both a factor of 100.
B<Callback handler prototype:>
sub spin_cb_handler {
my ($self, $inc) = @_;
#...
}
=back
=head1 EXAMPLES
Unfortunately there are no sample scripts using this element.
=head1 SEE ALSO
L<IUP::Text|IUP::Text>, L<IUP::Vbox|IUP::Vbox>,
L<IUP::Hbox|IUP::Hbox>, L<IUP::Button|IUP::Button>
The original doc: L<iupspin.html|http://www.tecgraf.puc-rio.br/iup/en/elem/iupspin.html>
=cut