#!/usr/bin/perl
use warnings;
use strict;
use Glib qw/TRUE FALSE/;
use Gtk2 '-init';

my $resize_flag = 0; #global for detecting a resize
my $ratio = .5; #global to store the adjustment setting
                #start centered
my $window = Gtk2::Window->new('toplevel');
$window->set_title('Adjustment Demo');
$window ->signal_connect( 'destroy' => \&delete_event );
$window->set_border_width(10);
$window->set_default_size(400,400);

my $vbox = Gtk2::VBox->new( FALSE, 6 );
$vbox->set_size_request(0,0);

$window->add($vbox);
$vbox->set_border_width(2);

my $hbox= Gtk2::HBox->new( FALSE, 6 );
$vbox->pack_end($hbox,FALSE,FALSE,0);
$hbox->set_border_width(2);

$vbox->pack_end (Gtk2::HSeparator->new, FALSE, FALSE, 0);

my $button = Gtk2::Button->new_from_stock('gtk-quit');
$hbox->pack_end( $button, FALSE, FALSE, 0 );
$button->signal_connect( clicked => \&delete_event );

# HPaned or VPaned are just types of Gtk2::Paned
# add to them with add1 and add2
my $hpaned = Gtk2::HPaned->new;
  $hpaned->set_border_width (5); 
  my $frame = Gtk2::Frame->new("Foo Label");
  my $label = Gtk2::Label->new("This is a  foo Label");
  $frame->add($label); 
 $hpaned->add1($frame);
  $vbox->pack_start ($hpaned, TRUE, TRUE, 0);

  my $frame1 = Gtk2::Frame->new("Bar Label");
  my $label1 = Gtk2::Label->new("This is a  bar Label");
  $frame1->add($label1);
  $hpaned->add2($frame1);

$window->show_all();

#setup as centered
set_position_by_ratio($hpaned);

$window->signal_connect (event_after => \&event_after);
$hpaned->signal_connect( event_after => \&set_ratio );

Gtk2->main;
#####################################
sub delete_event {
Gtk2->main_quit;
return FALSE;
}  
#######################################
sub event_after {
  my ($mw, $event) = @_;
#  print $event->type,"\n";
 # this tests so that the reconfiguring only occurs once after
 # the resize is finished 
 if( ($event->type eq 'configure') or ($event->type eq 'expose' ) ){
     $resize_flag = 1
   }else{ $resize_flag = 0  }
  
   if( ($event->type eq 'enter-notify') 
         or ($event->type eq 'leave-notify' ) 
           or ( $resize_flag == 1 ) 
       ){ return FALSE }
  
#   print $event->type,"\n";
    set_position_by_ratio($hpaned);

  return FALSE;
}
##########################################
sub set_ratio{
  # done only after an adjustment slide
  my ($pane, $event) = @_;
   if($event->type eq 'button-release'){
       my $rect = $pane->allocation;
       my ($x, $y, $width, $height) = $rect->values;
       my $new_width = $width -2*$x;
       my $pos = $pane->get_position;
       $ratio = $pos/$new_width;
       #print "$ratio\n";
 }
  return FALSE;
}
#############################################
sub set_position_by_ratio{
  my $pane = shift; 
  my $rect = $pane->allocation;
  my ($x, $y, $width, $height) = $rect->values;
  my $pos = ($width -2*$x) * $ratio;
  $pane->set_position($pos);
  #print "$ratio\n"; 
}
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