It looks to me like your Tk version is a little old. What do you get if you run:

perl -MTk -e "print $Tk::VERSION"
[download]

If you have something lower than 804.027, you should consider upgrading.

To handle changing the backgound colors of your script without needing to specify each widget, pass a pointer to the top level widget and recursively iterate over its children. Something like this. (replace the sub butone in your example script with these two subs.)

sub butone {
    my $color = $diswindow->chooseColor(
        -initialcolor => $colour,
        -title        => 'Choose color'
    );
    if ($color) {
        $colour = $color;
        my ( $r, $g, $b ) = $colour =~ /\w{2}/g;
        for ( $r, $g, $b ) {
            $_ = hex $_;
        }
        my $foreground = ( $r + $g + $b < 400 ) ? '#ffffff' : '#000000
+';
        change_colors( $diswindow, $colour, $foreground );
    }
}

sub change_colors {
    my ( $widget, $color, $fg ) = @_;
    $widget->configure( -bg => $color );
    {
        no warnings 'uninitialized';
        eval( $widget->configure( -foreground => $fg ) );
    }
    if ( my @children = $widget->children ) {
        change_colors( $_, $color, $fg ) for @children;
    }
}
[download]

Note that this also adjusts the foreground color to compensate for too dark or too light backgrounds.