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=head2 Customizing the Headline

You may provide a custom C<headline> method to generate a HTML chunk
to start your screens.

  sub headline { $_[0]->h1(title(@_)) }

You should overwrite the C<application> method if you use the default
title and headline.

  sub application { 'CGI::Screen Test' }

=head2 Customizing the Trailer

For a custom Trailer, define the C<trailer> method.

  sub trailer {
    my ($query, $screen)  = shift;
  
    "End of Screen $screen";
  }

=head2 Multiple Forms

If you want to have multiple forms on one screen, call the method
C<new_form>.

  sub multi_screen {
     my $query = shift;

     print
       $query->p('This is the Main Screen'),
       $query->textfield('foo'),
       $query->goto('First'),
       $query->new_form,
       $query->textfield('foo'),
       $query->goto('Second');
  }

=head2 Non HTML screens

You can create non HTML screens by defining a I<name>C<_data> method
instead of a <name>C<_screen> method. For C<data> screens you have
to generate HTTP headers yourself.

  sub gif_data {
    my $query = shift;
    
    print $query->header(
                         -type    => 'image/gif',
                         -status  => '200 OK',
                         -expires => '+120s',
                        );
    my $font  = $query->param('font');
    my $w     = GD::Font->$font()->width;
    my $h     = GD::Font->$font()->height;
    my $im    = GD::Image->new((length($query->param('foo'))+2)*$w,$h);
    my $white = $im->colorAllocate(255,255,255);
    my $red   = $im->colorAllocate(255,0,0);
    my $black = $im->colorAllocate(0,0,0);
    $im->transparent($white);
    $im->arc(8,8,5,5,0,360,$red);
    $im->string(GD::Font->$font(),10,0,$query->param('foo'),$black);
    print $im->gif;
  }

=head2 Keeping parameter values

CGI::Screen keeps track of the CGI parameters used in the current
form. It simply looks at the first parameter in any call to a CGI
method.  If the first parameter is C<-name>, the second parameter is
marked as I<used parameter>.  CGI::Screen passed all current parameter
values not used in hidden fields or in the query string of an
anchor. So do not use old style CGI calls to bypass this mechanism or
you will end up with multiple values for the parameters.

If you want to get rid of a parameter, you must explicitly call the
C<delete> method of CGI.

=head1 BUGS

Support for importing from CGI.pm is incomplete.

=head1 AUTHOR

Ulrich Pfeifer E<lt>F<pfeifer@wait.de>E<gt>

=head1 SEE ALSO

The CGI(3) manual and the demo CGI script F<eg/screen> included in the
distribution.

=head1 ACKNOWLEDGEMENTS

I wish to thank Andreas Koenig F<koenig@kulturbox.de> for the
fruitful discussion about the design of this module. 

=head1 Copyright

The B<CGI::Screen> module is Copyright (c) 1997,1998 Ulrich
Pfeifer. Germany.  All rights reserved.

You may distribute under the terms of either the GNU General Public
License or the Artistic License, as specified in the Perl README file.

=cut