You only need a new id when creating a new icon? You don't need to keep track of it? Seems like a good case to enclose a lexical: 
my $id = 1;

sub Yes_Mail {
    $main_window->TrayIconMailNo->{-id});
    $main_window->{'TrayIconMailNo'}->DESTROY();
    $main_window->AddNotifyIcon (
        -icon    => $tray_icon_file_mail_yes,
        -id      => $id++,
        -name    => "TrayIconMailYes",
        -tip     => "LupoX POP3 Notifier(TM) - YOU HAVE MAIL"
);

[download]
I'm not a Win32 programmer by any means, but that's how I understand your requirements.

A couple of other things could be stronger. Build a hash of event numbers and handlers instead of a large if/else switch: 

my %events = (
    512 => sub { print "mouse over icon\n" },
    513 => sub { print "left button clicked\n"; },
    # et cetera
);

if (exists $events{$msg}) {
    $events{$msg}->();
}

[download]

You can also avoid reading all of the lines in a file to see if there are new messages: 

open (NEW, 'mail.tmp') or die "Cannot open mail.tmp: $!\n";
if (defined(my $line = <NEW>)) {
    Yes_Mail();
}
close NEW;

[download]

In reply to Re: Win32::GUI Task Bar Icon Bug or bad programming? by chromatic
in thread Win32::GUI Task Bar Icon Bug or bad programming? by LupoX

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