+AC_ARG_WITH([quartz],
+ [AS_HELP_STRING([--with-quartz],
+ [build for the MacOS Quartz GTK back end])],
+ [AC_DEFINE([OSX_GTK], [1], [Define if building with GTK for MacOS.])
+ with_quartz=yes],
+ [with_quartz=no])
+
+AM_CONDITIONAL([HAVE_QUARTZ],[test "x$with_quartz" = "xyes"])
+