Here is the first way, using Win32::GuiTest.

use strict;
use Win32::GuiTest qw(FindWindowLike GetChildWindows GetWindowText
                      GetWindowID SetActiveWindow SetForegroundWindow
                      PostMessage);

sub WM_LBUTTONDOWN      { 0x0201; }
sub WM_LBUTTONUP        { 0x0202; }

my @winlst;
my $tries = 0;
while ($tries < 20) {
   print "trying to find the window\n";
   @winlst = FindWindowLike(0,'StatusBar','TkTopLevel');
   last if scalar(@winlst) > 0;
   $tries++;
   sleep 1;
}
if (@winlst == 1) {
   my $status = $winlst[0];

   my $i;
   my $x = 30;
   my $y = 14;
   my $xy = ($y << 16) + $x;
   print "trying to send a click to the window\n";
   SetForegroundWindow($status);
   SetActiveWindow($status);
   PostMessage($status, WM_LBUTTONDOWN, 0x0001, $xy);
   PostMessage($status, WM_LBUTTONUP, 0, $xy);
}
[download]

Here is the second way, using Win32::CtrlGUI.

use strict;
use Win32::CtrlGUI;

my $win = Win32::CtrlGUI::wait_for_window("ParpadStatus");
my $x = 30;
my $y = 14;
my $xy = ($y << 16) + $x;
print "trying to send a click to the window ",
   sprintf("0x%lx",$win->handle),"\n";
$win->post_message('NN', "WM_LBUTTONDOWN", 0x0001, $xy);
$win->post_message('NN', "WM_LBUTTONUP", 0, $xy);
[download]

In both cases Spy++ shows that the window is getting the button events, but it isn't responding. There are also some unusual messages in the log in both cases about a message 0x118:

003000BE R WM_ACTIVATE
003000BE P WM_LBUTTONDOWN fwKeys:MK_LBUTTON xPos:30 yPos:14
003000BE P WM_LBUTTONUP fwKeys:MK_LBUTTON xPos:30 yPos:14
003000BE P message:0x118 [Unknown] wParam:0000FFF8 lParam:A00885B9
003000BE S WM_NCACTIVATE fActive:False
003000BE R WM_NCACTIVATE fDeactivateOK:True
[download]

Does anyone have ideas about how I can get this to work, or if I should abandon it for better ways? I would rather not use sockets, because later I want to communicate asynchronously with other more complicated perl/Tk applications.