my 	$MamaGUI       = new MainWindow( -title => "Mein Programm");

# Größe des Fensters:
my 	$windowHeight  = "600";
my 	$windowWidth   = "800";

# Bildschirmgröße holen:
my 	$screenHeight  = $MamaGUI->screenheight;
my 	$screenWidth   = $MamaGUI->screenwidth;

# MamaGUI zentrieren:
$MamaGUI->geometry($windowWidth."x".$windowHeight);
$MamaGUI->geometry("+" .
                    int($screenWidth/2 - $windowWidth/2) .
                    "+" .
                    int($screenHeight/2 - $windowHeight/2)
                   );