It's all about packing order. You were placing the labels over the top of each other. Try this:

#!/usr/bin/perl -w
use strict;

use strict;
use warnings;

use Tk;
use Tk::DialogBox;

my $main_window = MainWindow -> new();

$main_window -> bind ( "<Control-Key-c>" , \&add_client ) ; # Ctrl c

MainLoop;

sub add_client {

  my $add_client_win = $main_window -> DialogBox (
    
    -title => 'Ajouter un client' ,
    -buttons => [ 'Valider' , 'Annuler' ]
  );

    # BUG HERE BUG HERE BUG HERE BUG HERE BUG HERE BUG HERE BUG HERE 
    
    my $firstname_line = $add_client_win -> add ( 'Label' , 

        -height => '5',
    -text => 'Some text',
        -font => 'Helvetica 10 bold' ,
        
    ) -> grid(

        #-side => 'top' ,
        #-fill => 'x'
    );
        
    # END BUG END BUG END BUG END BUG END BUG END BUG END BUG END BUG 
     
    # -- CANTON --
    
    my $canton_line = $add_client_win -> add ( 'Label' , 
    
        -height => '5'
        
    ) -> grid(
    
        #-side => 'top' ,
        #-fill => 'x'
    );
    
  my $label_canton = $canton_line -> Label (

        -font => 'Helvetica 10 bold' ,
    -text => 'Localisation :',
        -padx => '10' ,
        -pady => '5'
        
    ) -> pack (
    
        -side => 'left' 
    );
    
    my ($canton_data, $canton_display );

    my $canton_choice = $canton_line -> Optionmenu(

        -options => [
            [ 'Genève' =>               '000' ] , 
            [ 'Vaud' =>                 '100' ] , 
            [ ' - Chablais vaudois' =>  '110' ] , 
            [ ' - Lausanne' =>          '120' ] ,
            [ ' - Montreux-Vevey' =>    '130' ] ,
            [ ' - Morges' =>            '140' ] ,
            [ ' - Nyon' =>              '150' ] ,
            [ ' - Yverdon' =>           '160' ] ,
            [ ' - Arc lémanique' =>     '170' ] ,
            [ 'Valais' =>               '200' ] ,
            [ ' - Chablais valaisan' => '210' ] ,
            [ ' - Bas Valais' =>        '220' ] ,
            [ ' - Haut Valais' =>       '230' ] ,
            [ 'Fribourg' =>             '400' ] ,
            [ 'France voisine' =>       '500' ] ,
            [ 'Paris' =>                '600' ] ,
            [ 'Cote d Azur' =>          '700' ] ,
            [ 'Italie' =>               '800' ] ,
            
            ] ,
        -command => sub { } ,
    -variable => \$canton_data ,
    -textvariable => \$canton_display
        
    ) -> pack(
    
        -side => 'right' ,
    );
    
  my $reponse = $add_client_win -> Show ( ) ;    
}
[download]

By using the  grid geometry manager they are placed vertically in order in a grid.

jdtoronto

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.