GUI Perl

#!/usr/bin/perl -w
use Tk;
use Tk::FileSelect;
$main = MainWindow->new();
$menubar = $main->Frame(-relief=>"raised",
                        -borderwidth=>2);
$filebutton = $menubar->Menubutton(-text=>"File",
                                   -underline => 0);  # F in File
$filemenu = $filebutton->Menu();
$filebutton->configure(-menu=>$filemenu);
$filemenu->command(-command => \&open_choice,
                   -label => "Open...",
                   -underline => 0); # O in Open
$filemenu->command(-command => \&dump_choice,
                   -label => "Dump",
                   -underline => 0); # D in Dump
$filemenu->separator();
$filemenu->command(-label => "Exit",
                   -command => \&exit_choice,
                   -underline => 1);  # "x" in Exit
$filebutton->pack(-side=>"left");
$menubar->pack(-side=>"top", -fill=>"x");
$text = $main->Scrolled('Text',
                        -relief      => "sunken",
                        -borderwidth => 2,
                        -setgrid     => "true",
                        -scrollbars  => 'se' );
$text->pack(-side=>"top", 
            -expand => 1,
            -fill => 'both');
$file_dialog = $main->FileSelect(-directory => ".");
MainLoop();
sub exit_choice {
    print "You chose the Exit choice!\n";
    exit;
}
sub open_choice {
    $filename = $file_dialog->Show();
    
    if ($filename ne "" ) {
        open (FILE, $filename);
        $text->delete("1.0", "end");
        while ($txt = ) {
            $text->insert("end", $txt);
        }
        close(FILE);
    }
}
sub dump_choice {
    print $text->get("1.0", "end");
}