+###############################################################################
+#
+# Check for the XF86VMODE server extension (for gamma fading.)
+#
+###############################################################################
+
+have_xf86gamma=no
+with_xf86gamma_req=unspecified
+AC_ARG_WITH(xf86gamma-ext,
+[ --with-xf86gamma-ext Include support for XFree86 gamma fading.],
+ [with_xf86gamma="$withval"; with_xf86gamma_req="$withval"],
+ [with_xf86gamma=yes])
+
+HANDLE_X_PATH_ARG(with_xf86gamma, --with-xf86gamma-ext, xf86gamma)
+
+if test "$with_xf86gamma" = yes; then
+
+ # first check for xf86vmode.h, if we haven't already
+ if test "$have_xf86vmode" = yes; then
+ have_xf86gamma=yes
+ else
+ AC_CHECK_X_HEADER(X11/extensions/xf86vmode.h, [have_xf86gamma=yes])
+ fi
+
+ # if that succeeded, then check for the -lXxf86vm
+ if test "$have_xf86gamma" = yes; then
+ have_xf86gamma=no
+ AC_CHECK_X_LIB(Xxf86vm, XF86VidModeSetGamma,
+ [have_xf86gamma=yes],
+ [true], -lXext -lX11)
+ fi
+
+ # pull in the lib, if we haven't already
+ if test "$have_xf86gamma" = yes -a "$have_xf86vmode" = no; then
+ SAVER_LIBS="$SAVER_LIBS -lXxf86vm"
+ fi
+
+ # if that succeeded, then we've really got it.
+ if test "$have_xf86gamma" = yes; then
+ AC_DEFINE(HAVE_XF86VMODE_GAMMA)
+ fi
+
+elif test "$with_xf86gamma" != no; then
+ echo "error: must be yes or no: --with-xf86gamma-ext=$with_xf86vmode"
+ exit 1
+fi
+
+