use Tk;
use Win32::Clipboard;
use Win32::Process;
$::CLIP = Win32::Clipboard();

# lots of code here

Win32::Process::Create($ProcessObj,
		"d:\\mwa\\perlpps\\mwebprep.exe",
		"mwebprep $step",
		0,
		NORMAL_PRIORITY_CLASS,
		".")
|| die Win32ProcessError();

my $emptytries = 0;
my $clip;
while (1)
{
	$clip = Win32::Clipboard::GetText();
	if ($clip)
	{
		$::progresstext->insert('end', $clip . "\n");
		$::progresstext->yview('moveto', 100);
		$::mainwin->update;
		$::CLIP->Empty();
		$emptytries = 0;
		sleep(5);
	}
	else
	{
		$emptytries++;
		last if ($emptytries >= 3);
		sleep(1);
	}
}

$ProcessObj->Wait(INFINITE);

# more code