only add file dialog separators on mac

Fltk/menuWindow.cpp

@@ -81,9 +81,14 @@ static void file_new_cb(Fl_Widget *w, void *data)
 #if defined(HAVE_NATIVE_FILE_CHOOSER)
 #  define TT "\t"
 #  define NN "\n"
+#  if defined(__APPLE__)
 #    define SEPARATOR_IN    " " TT "*" NN
 #    define SEPARATOR_OUT  {" " TT "*.*", _save_auto},
 #  else
+#    define SEPARATOR_IN
+#    define SEPARATOR_OUT
+#  endif
+#else
 #  define TT " ("
 #  define NN ")\t"
 #  define SEPARATOR_IN