Basically all code is just a change of the elements defined in the Populate method.

$Gui::DlgProcessDelay::VERSION = 0.1;

package Gui::DlgProcessDelay;


use Tk::widgets qw/Label Button Entry/;
use base qw/Gui::DlgBasic/;

use strict;
use warnings;
use Carp qw/carp cluck/;

use Data::Dumper;


Construct Tk::Widget 'DlgProcessDelay';

# Initialising the object
# 
sub ClassInit{

  my ( $class, $mw ) = @_;
  $class->SUPER::ClassInit( $mw );

} # END: ClassInit


# Populating the widget
sub Populate{

  my ( $self, $args ) = @_;
  $self->SUPER::Populate( $args );

  $self->ConfigSpecs( -xlssource => [qw/METHOD xlssource XlsSource/],
              -xlstarget => [qw/METHOD xlstarget XlsTarget/], 
            );

  $self->{ _frmDelay } =
    $self->Frame( -label =>  "Delay Data" )
      ->grid( -row     => 0,
          -column     => 0,
          -sticky     => 'w' );





  $self->{ _frmDelay }->Label( -text => "Delay Source:" )
    ->grid( -row    => 0,
        -column    => 0,
        -sticky    => 'w' );

  $self->{ _frmDelay }->Label( -text => "Import Delay Data:" )
    ->grid( -row    => 0,
        -column    => 1,
        -sticky    => 'w' );

  $self->{ _entDelayData  } = 
    $self->{ _frmDelay }->Entry( -textvariable => \$self->{ _sXlsSourc
+e },
                 -borderwidth => 2,
                 -width => 60,
                 -relief => 'groove' )
      ->grid( -row    => 1,
          -column    => 1,
          -columnspan => 3,
          -sticky    => 'w' );
  
  $self->{ _frmDelay }->Button( -text => "...",
                -command => sub { $self->_getXlsSource(); } )
    ->grid( -row    => 2,
        -column    => 2,
        -sticky    => 'w' );
  
  $self->{ _frmDelay }->Button( -text => "Import File",
                -command => sub { $self->_importXlsFile(); } )
    ->grid( -row    => 2,
        -column    => 3,
        -sticky    => 'w' );

} # end Populate

# Configure the delay import sourcefile name
#
sub xlssource{

    my $self = shift;

    if ( @_ > 0 ) {
      
      my $file = shift;

      if ( -e $file ) {

    $self->{ _sXlsSource } = $file;

      } # END: if ( -e $file )
      
      else {
    
    cluck "You tried to load a file non-existing file.";

      } # END: else ( -e $file )

    } # END: if ( @_ > 0 )
    else {

      # cluck "Monitored a cget on option -ciffile.\n"; 
      return $self->{ _sXlsSource };    # cget(  ) requests here


    } # END: else ( @_ > 0 }

}


# Configure the xls target name
#
sub xlstarget{

  my $self = shift;

  if ( @_ > 0 ) {

    my $file = shift;

    $self->{ _sXlsTarget } = $file;

  } # END: if ( @_ > 0 )
  else {

    # cluck "Monitored a cget on option -ciffile.\n"; 
    return $self->{ _sXlsTarget };    # cget(  ) requests here

  } # END: else ( @_ > 0 }

}


sub _getXlsSource{

  my ( $self ) = @_;
  my $file = Gui::Misc::open_file( $self, "xls" );
  $self->configure( -xlssource => $file );

}

sub _importXlsSource{

  print "Not yet implemented.\n";

}

sub _getXlsTarget{

  my ( $self ) = @_;
  my $file = Gui::Misc::save_file( $self, "xls" );
  $self->configure( -xlstarget => $file );

}
1;
[download]

It seems to run fine through Populate. But hangs somewhere afterwards.