use Tk;

# Experimental mousewheel support. This should really be part of Tk.
# XXX <MouseWheel> support for Windows is untested.
BEGIN {
    if ($Tk::VERSION < 804) {
    local $^W = 0;
    require Tk::Listbox;
    my $orig_tk_listbox_classinit = \&Tk::Listbox::ClassInit;
    *Tk::Listbox::ClassInit = sub {
        my($class,$mw)=@_;
        $orig_tk_listbox_classinit->(@_);
        $mw->bind($class, "<4>", ['yview', 'scroll', -5, 'units']);
        $mw->bind($class, "<5>", ['yview', 'scroll', +5, 'units']);
        $mw->bind($class, '<MouseWheel>',
              [ sub { $_[0]->yview('scroll',-($_[1]/120)*3,'units') }, Tk::Ev("D")]);
    };