+HAVE_CARBON=no
+if test "${with_carbon}" != no; then
+ AC_CHECK_HEADER(Carbon/Carbon.h, HAVE_CARBON=yes)
+fi
+if test "${window_system}" = x11 && test "${HAVE_CARBON}" = yes; then
+ if test "${with_carbon+set}" != set \
+ && test "${carbon_appdir_x+set}" != set; then
+ HAVE_CARBON=no
+ fi
+fi
+if test "${HAVE_CARBON}" = yes; then
+ window_system=mac
+fi
+