This patch was made against the version of grub provided in the Debian archive, namely 0.93 + cvs 20030224. It should also work with grub-0.92 and with grub patched for the el-torito hd boot image, available on the internet in a file named ``grub-0.92.a_cd+ef.diff.gz'' (this is the patch needed by mkbimage). At most you will get a reject in stage2/builtins.c, since patch is not able to understand where to add the line ``&builtin_showdefault, '' in builtin_table[]. Since you are a human being, you should be able to insert it in the correct place. Just look for ``builtin_table'' in your builtins.c and add the line I told you about on any line by itself as long as the alphabetical order of the listed commands is maintained.
This patch is just one morning effort, so, don't blame me too much if you have troubles. It actually took me longer to write this document than to code the patch. If you have troubles using it, I'd be glad to give you as much help as you may need. Just mail me at <ccontavalli at commedia.it>.
To use the patch, you just need a standard:
$ cd grub_sources
$ cat path_to_my_patch/grub-patch-x.y.diff |patch -p1