function OpenWindow(hoog,breed) {
    var window_height = hoog;
    var window_width  = breed;
    var window_dimensions = "height=" + window_height + ",width=" + window_width +                        ",left=0,top=0,resizable=yes,scrollbars=yes";
    hello=window.open('kaart.php', 'kaart', window_dimensions);
}