this is a bashism but might be from ksh93 IIRC… still dead ugly as hell!

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.396 2010/11/01 17:29:00 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.397 2010/12/19 20:00:53 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -25,7 +25,7 @@
 # http://www.research.att.com/~gsf/public/ifs.sh
 
 expected-stdout:
-	@(#)MIRBSD KSH R39 2010/11/01
+	@(#)MIRBSD KSH R39 2010/12/19
 description:
 	Check version of shell.
 stdin:
@@ -5984,6 +5984,22 @@ expected-stdout:
 	000000B0  E2 82 AC 64 20 EF BF BD - 20 12 33 20 78 20 53 20  |...d ... .3 x S |
 	000000C0  53 34 0A                -                          |S4.|
 ---
+name: dollar-doublequoted-strings
+description:
+	Check that a $ preceding "…" is ignored
+stdin:
+	echo $"Localise me!"
+	cat <<<$"Me too!"
+	V=X
+	aol=aol
+	cat <<-$"aol"
+		I do not take a $V for a V!
+	aol
+expected-stdout:
+	Localise me!
+	Me too!
+	I do not take a $V for a V!
+---
 name: dollar-quoted-strings
 description:
 	Check backslash expansion by $'…' strings

lex.c

@@ -22,7 +22,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/lex.c,v 1.121 2010/09/14 21:26:14 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/lex.c,v 1.122 2010/12/19 20:00:54 tg Exp $");
 
 /*
  * states while lexing word
@@ -485,9 +485,13 @@ yylex(int cf)
 					PUSH_STATE(SEQUOTE);
 					statep->ls_sequote.got_NUL = false;
 					break;
+				} else if (c == '"' && (state == SBASE)) {
+					/* XXX which other states are valid? */
+					goto DEQUOTE;
 				} else {
 					*wp++ = CHAR;
 					*wp++ = '$';
+ DEQUOTE:
 					ungetsc(c);
 				}
 				break;
@@ -834,7 +838,8 @@ yylex(int cf)
 					PUSH_STATE(SEQUOTE);
 					statep->ls_sequote.got_NUL = false;
 					goto sherestring_quoted;
-				}
+				} else if (c2 == '"')
+					goto sherestring_dquoted;
 				ungetsc(c2);
 				goto sherestring_regular;
 			} else if (c == '\'') {
@@ -845,6 +850,7 @@ yylex(int cf)
 				/* invoke quoting mode */
 				Xstring(ws, wp)[0] = QCHAR;
 			} else if (c == '"') {
+ sherestring_dquoted:
 				state = statep->ls_state = SHEREDQUOTE;
 				*wp++ = OQUOTE;
 				/* just don't IFS split; no quoting mode */
@@ -876,7 +882,8 @@ yylex(int cf)
 					PUSH_STATE(SEQUOTE);
 					statep->ls_sequote.got_NUL = false;
 					goto sheredelim_quoted;
-				}
+				} else if (c2 == '"')
+					goto sheredelim_dquoted;
 				ungetsc(c2);
 				goto sheredelim_regular;
 			} else if (c == '\'') {
@@ -885,6 +892,7 @@ yylex(int cf)
 				*wp++ = OQUOTE;
 				ignore_backslash_newline++;
 			} else if (c == '"') {
+ sheredelim_dquoted:
 				state = statep->ls_state = SHEREDQUOTE;
 				*wp++ = OQUOTE;
 			} else {

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.242 2010/10/08 17:30:05 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.243 2010/12/19 20:00:55 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.138 2010/09/20 07:41:17 jmc Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
@@ -71,7 +71,7 @@
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
-.Dd $Mdocdate: October 8 2010 $
+.Dd $Mdocdate: December 19 2010 $
 .\"
 .\" Check which macro package we use
 .\"
@@ -971,6 +971,9 @@ If a single-quoted string is preceded by an unquoted
 C style backslash expansion (see below) is applied (even single quote
 characters inside can be escaped and do not terminate the string then);
 the expanded result is treated as any other single-quoted string.
+If a double-quoted string is preceded by an unquoted
+.Ql $ ,
+the latter is ignored.
 .Ss Backslash expansion
 In places where backslashes are expanded, certain C and
 .At

sh.h

@@ -154,9 +154,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.419 2010/11/01 17:29:05 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.420 2010/12/19 20:00:56 tg Exp $");
 #endif
-#define MKSH_VERSION "R39 2010/11/01"
+#define MKSH_VERSION "R39 2010/12/19"
 
 #ifndef MKSH_INCLUDES_ONLY