use Win32::GUI; 
my $screen_width = Win32::GUI::GetSystemMetrics(0);
my $screen_height = Win32::GUI::GetSystemMetrics(1);
my $minwidth = 620;
my $minheight = 255; 
my $MainWindow = new Win32::GUI::Window(
    -name => "MainWindow",
    -top => ($screen_height - $minheight)/2,
    -left => ($screen_width - $minwidth)/2,
    -width => $minwidth,
    -height => $minheight,
    -minsize=> [$minwidth,$minheight],
    -title => "Sample Window",
); 
$HostName = $MainWindow->AddCombobox(
    -name => "HostName",
    -tabstop => 1,
    -style => WS_VISIBLE | 2 | WS_NOTIFY,
    -left => 205,
    -top => 10,
    -width => 110,
    -height => 160,
);
$HostName->InsertItem ("ftp.server1.com");
$HostName->InsertItem ("ftp.server2.com"); 

$MainWindow->Show();
$HostName->Select(0); 

Win32::GUI::Dialog();