-dnl Check in -lXext for double buffering extensions to X11, and check
-dnl whether appropriate header files are present. (Some systems have one
-dnl but not the other.)
-our_saved_LDFLAGS="$LDFLAGS"
-LDFLAGS="$X_LIBS $LDFLAGS"
-AC_CHECK_LIB(Xext, XdbeQueryExtension, AC_DEFINE(HAVE_DBE_SUPPORT,1,[x dbe support]), , -lX11 "$X_EXTRA_LIBS")
-AC_CHECK_LIB(Xext, XmbufQueryExtension, AC_DEFINE(HAVE_MBX_SUPPORT,1,[x mbx support]), , -lX11 "$X_EXTRA_LIBS")
-LDFLAGS="$our_saved_LDFLAGS"
-our_saved_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$X_CFLAGS $CPPFLAGS"
-AC_CHECK_HEADERS(X11/extensions/Xdbe.h X11/extensions/multibuf.h)
-CPPFLAGS="$our_saved_CPPFLAGS"
-