+# Check for the DOUBLE-BUFFER server extension header.
+#
+have_xdbe=no
+with_xdbe_req=unspecified
+AC_ARG_WITH(xdbe-ext,
+[ --with-xdbe-ext Include support for the DOUBLE-BUFFER server
+ extension, if possible (this is the default).
+ --without-xdbe-ext Do not compile in support for this extension.],
+ [with_xdbe="$withval"; with_xdbe_req="$withval"],[with_xdbe=yes])
+
+HANDLE_X_PATH_ARG(with_xdbe, --with-xdbe-ext, DOUBLE-BUFFER)
+
+if test "$with_xdbe" = yes; then
+
+ AC_CHECK_X_HEADER(X11/extensions/Xdbe.h, [have_xdbe=yes])
+ if test "$have_xdbe" = yes; then
+ AC_DEFINE(HAVE_DOUBLE_BUFFER_EXTENSION)
+ fi
+
+elif test "$with_xdbe" != no; then
+ echo "error: must be yes or no: --with-xdbe-ext=$with_xshm"
+ exit 1
+fi
+
+