# Rahmen entfernen
$mw->overrideredirect(1);  

# im Vordergrund belassen
my $win32_winpos = Win32::API->new(
    'user32', 'SetWindowPos',
    ['N','N','N','N','N','N','N'], 'N'
);
$mw->update;
$win32_winpos->Call(hex($mw->frame()),-1,0,0,0,0,3);