+#if wxUSE_GZSTREAM
+# if !wxUSE_ZLIB
+# ifdef wxABORT_ON_CONFIG_ERROR
+# error "wxUSE_GZSTREAM requires wxUSE_ZLIB"
+# else
+# undef wxUSE_ZLIB
+# define wxUSE_ZLIB 1
+# endif
+# endif
+#endif /* wxUSE_GZSTREAM */
+
+/* have to test for wxUSE_HTML before wxUSE_FILESYSTEM */
+#if wxUSE_HTML
+# if !wxUSE_FILESYSTEM
+# ifdef wxABORT_ON_CONFIG_ERROR
+# error "wxHTML requires wxFileSystem"
+# else
+# undef wxUSE_FILESYSTEM
+# define wxUSE_FILESYSTEM 1
+# endif
+# endif
+#endif /* wxUSE_HTML */
+
+#if wxUSE_FILESYSTEM
+# if !wxUSE_STREAMS
+# ifdef wxABORT_ON_CONFIG_ERROR
+# error "wxUSE_FILESYSTEM requires wxUSE_STREAMS"
+# else
+# undef wxUSE_STREAMS
+# define wxUSE_STREAMS 1
+# endif
+# endif
+#endif /* wxUSE_FILESYSTEM */
+
+#if wxUSE_FS_INET
+# if !wxUSE_PROTOCOL
+# ifdef wxABORT_ON_CONFIG_ERROR
+# error "wxUSE_FS_INET requires wxUSE_PROTOCOL"
+# else
+# undef wxUSE_PROTOCOL
+# define wxUSE_PROTOCOL 1
+# endif
+# endif
+#endif /* wxUSE_FS_INET */
+
+#if wxUSE_STOPWATCH || wxUSE_DATETIME