+# Check for the DOUBLE-BUFFER server extension header.
+#
+have_xdbe=no
+with_xdbe_req=unspecified
+# Check whether --with-xdbe-ext or --without-xdbe-ext was given.
+if test "${with_xdbe_ext+set}" = set; then
+ withval="$with_xdbe_ext"
+ with_xdbe="$withval"; with_xdbe_req="$withval"
+else
+ with_xdbe=yes
+fi
+
+
+
+ case "$with_xdbe" in
+ yes) ;;
+ no) ;;
+
+ /*)
+ echo $ac_n "checking for DOUBLE-BUFFER headers""... $ac_c" 1>&6
+echo "configure:4209: checking for DOUBLE-BUFFER headers" >&5
+ d=$with_xdbe/include
+ if test -d $d; then
+ X_CFLAGS="-I$d $X_CFLAGS"
+ echo "$ac_t""$d" 1>&6
+ else
+ echo "$ac_t""not found ($d: no such directory)" 1>&6
+ fi
+
+ echo $ac_n "checking for DOUBLE-BUFFER libs""... $ac_c" 1>&6
+echo "configure:4219: checking for DOUBLE-BUFFER libs" >&5
+ d=$with_xdbe/lib
+ if test -d $d; then
+ X_LIBS="-L$d $X_LIBS"
+ echo "$ac_t""$d" 1>&6
+ else
+ echo "$ac_t""not found ($d: no such directory)" 1>&6
+ fi
+
+ # replace the directory string with "yes".
+ with_xdbe_req="yes"
+ with_xdbe=$with_xdbe_req
+ ;;
+
+ *)
+ echo ""
+ echo "error: argument to --with-xdbe-ext must be \"yes\", \"no\", or a directory."
+ echo " If it is a directory, then \`DIR/include' will be added to"
+ echo " the -I list, and \`DIR/lib' will be added to the -L list."
+ exit 1
+ ;;
+ esac
+
+ # why is this necessary?
+ # if we don't do this, then "./configure --with-motif=/usr/local/lesstif"
+ # behaves as if "--with-zippy=/usr/local/lesstif" was also present!
+ withval=
+
+
+if test "$with_xdbe" = yes; then
+
+
+ ac_save_CPPFLAGS="$CPPFLAGS"
+ if test \! -z "$includedir" ; then
+ CPPFLAGS="$CPPFLAGS -I$includedir"
+ fi
+ CPPFLAGS="$CPPFLAGS $X_CFLAGS"
+ ac_safe=`echo "X11/extensions/Xdbe.h" | sed 'y%./+-%__p_%'`
+echo $ac_n "checking for X11/extensions/Xdbe.h""... $ac_c" 1>&6
+echo "configure:4258: checking for X11/extensions/Xdbe.h" >&5
+if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
+ echo $ac_n "(cached) $ac_c" 1>&6
+else
+ cat > conftest.$ac_ext <<EOF
+#line 4263 "configure"
+#include "confdefs.h"
+#include <X11/extensions/Xdbe.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:4268: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
+if test -z "$ac_err"; then
+ rm -rf conftest*
+ eval "ac_cv_header_$ac_safe=yes"
+else
+ echo "$ac_err" >&5
+ echo "configure: failed program was:" >&5
+ cat conftest.$ac_ext >&5
+ rm -rf conftest*
+ eval "ac_cv_header_$ac_safe=no"
+fi
+rm -f conftest*
+fi
+if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
+ echo "$ac_t""yes" 1>&6
+ have_xdbe=yes
+else
+ echo "$ac_t""no" 1>&6
+fi
+
+ CPPFLAGS="$ac_save_CPPFLAGS"
+ if test "$have_xdbe" = yes; then
+ cat >> confdefs.h <<\EOF
+#define HAVE_DOUBLE_BUFFER_EXTENSION 1
+EOF
+
+ fi
+
+elif test "$with_xdbe" != no; then
+ echo "error: must be yes or no: --with-xdbe-ext=$with_xshm"
+ exit 1
+fi
+
+