my $starthwnd = $GetDesktopWindow->Call(); # get desktop window, all other windows are childs of this one

my $hwnd = $GetWindow->Call( $starthwnd, 5 ); # get first child window

while ($hwnd)
{
	my $is_visible = $IsWindowVisible( $hwnd );

	print "$hwnd ", ( $is_visible ? 'is' : 'is not' ), " visible\n";

	$hwnd = $GetWindow->Call( $hwnd, 2 ); # get next window
} # while