use Win32::Screenshot;
use Win32::GuiTest qw(FindWindowLike SetForegroundWindow);

my @windows = FindWindowLike(0,qr/^search.cpan.org/);

if (defined($windows[0])) {
    
    SetForegroundWindow($windows[0]);
    my $image = CaptureWindow($windows[0]);
    $image->Write('screenshot.png');

}