--- Doc/Zsh/options.yo	18 Mar 2005 22:40:17 -0000	1.37
+++ Doc/Zsh/options.yo	14 Jul 2005 17:49:54 -0000
@@ -906,6 +906,15 @@ Print a carriage return just before prin
 a prompt in the line editor.  This is on by default as multi-line editing
 is only possible if the editor knows where the start of the line appears.
 )
+pindex(PROMPT_SP)
+cindex(prompt, save partial lines)
+item(tt(PROMPT_SP) (tt(PLUS()V)) <D>)(
+Attempt to preserve any partially-output line (i.e. a line that did not end
+with a newline) by outputting a series of spaces prior to the carriage return
+that is output by PROMPT_CR.  This only works if your terminal has automatic
+margins.  Also, if the PROMPT_CR option is not set, enabling this option will
+have no effect.  This option is on by default.
+)
 pindex(PROMPT_PERCENT)
 cindex(prompt, % expansion)
 item(tt(PROMPT_PERCENT) <C> <Z>)(
--- Src/init.c	13 Jun 2005 14:59:37 -0000	1.53
+++ Src/init.c	14 Jul 2005 17:49:55 -0000
@@ -77,7 +77,7 @@ mod_export int tclen[TC_COUNT];
 /**/
 int tclines, tccolumns;
 /**/
-mod_export int hasam;
+mod_export int hasam, hasxn;
 
 /* Pointer to read-key function from zle */
 
@@ -518,7 +518,7 @@ static char *tccapnams[TC_COUNT] = {
     "cl", "le", "LE", "nd", "RI", "up", "UP", "do",
     "DO", "dc", "DC", "ic", "IC", "cd", "ce", "al", "dl", "ta",
     "md", "so", "us", "me", "se", "ue", "ch",
-    "ku", "kd", "kl", "kr"
+    "ku", "kd", "kl", "kr", "sc", "rc", "bc"
 };
 
 /* Initialise termcap */
@@ -573,6 +573,7 @@ init_term(void)
 
 	/* check whether terminal has automargin (wraparound) capability */
 	hasam = tgetflag("am");
+	hasxn = tgetflag("xn"); /* also check for newline wraparound glitch */
 
 	tclines = tgetnum("li");
 	tccolumns = tgetnum("co");
@@ -587,10 +588,22 @@ init_term(void)
 	    termflags |= TERM_NOUP;
 	}
 
-	/* if there's no termcap entry for cursor left, use \b. */
+	/* most termcaps don't define "bc" because they use \b. */
+	if (!tccan(TCBACKSPACE)) {
+	    tcstr[TCBACKSPACE] = ztrdup("\b");
+	    tclen[TCBACKSPACE] = 1;
+	}
+
+	/* if there's no termcap entry for cursor left, use backspace. */
 	if (!tccan(TCLEFT)) {
-	    tcstr[TCLEFT] = ztrdup("\b");
-	    tclen[TCLEFT] = 1;
+	    tcstr[TCLEFT] = tcstr[TCBACKSPACE];
+	    tclen[TCLEFT] = tclen[TCBACKSPACE];
+	}
+
+	if (tccan(TCSAVECURSOR) && !tccan(TCRESTRCURSOR)) {
+	    tclen[TCSAVECURSOR] = 0;
+	    zsfree(tcstr[TCSAVECURSOR]);
+	    tcstr[TCSAVECURSOR] = NULL;
 	}
 
 	/* if the termcap entry for down is \n, don't use it. */
--- Src/options.c	18 Mar 2005 22:40:26 -0000	1.22
+++ Src/options.c	14 Jul 2005 17:49:55 -0000
@@ -181,6 +181,7 @@ static struct optname optns[] = {
 {NULL, "promptbang",	      OPT_KSH,			 PROMPTBANG},
 {NULL, "promptcr",	      OPT_ALL,			 PROMPTCR},
 {NULL, "promptpercent",	      OPT_NONBOURNE,		 PROMPTPERCENT},
+{NULL, "promptsp",	      OPT_ALL,			 PROMPTSP},
 {NULL, "promptsubst",	      OPT_KSH,			 PROMPTSUBST},
 {NULL, "pushdignoredups",     OPT_EMULATE,		 PUSHDIGNOREDUPS},
 {NULL, "pushdminus",	      OPT_EMULATE,		 PUSHDMINUS},
--- Src/zsh.h	1 Jun 2005 10:45:42 -0000	1.74
+++ Src/zsh.h	14 Jul 2005 17:49:55 -0000
@@ -1594,6 +1594,7 @@ enum {
     PROMPTBANG,
     PROMPTCR,
     PROMPTPERCENT,
+    PROMPTSP,
     PROMPTSUBST,
     PUSHDIGNOREDUPS,
     PUSHDMINUS,
@@ -1716,7 +1717,10 @@ struct ttyinfo {
 #define TCDOWNCURSOR   26
 #define TCLEFTCURSOR   27
 #define TCRIGHTCURSOR  28
-#define TC_COUNT       29
+#define TCSAVECURSOR   29
+#define TCRESTRCURSOR  30
+#define TCBACKSPACE    31
+#define TC_COUNT       32
 
 #define tccan(X) (tclen[X])
 
--- Src/Zle/zle_main.c	8 Apr 2005 16:58:21 -0000	1.68
+++ Src/Zle/zle_main.c	14 Jul 2005 17:49:56 -0000
@@ -962,8 +962,30 @@ zleread(char **lp, char **rp, int flags,
 	}
     }
     initundo();
-    if (isset(PROMPTCR))
+    if (isset(PROMPTCR)) {
+	/* The PROMPT_SP heuristic will move the prompt down to a new line
+	 * if there was any dangling output on the line (assuming the terminal
+	 * has automatic margins, but we try even if hasam isn't set). */
+	if (isset(PROMPTSP)) {
+	    if (hasxn) /* w/o this, a delayed wrap might be lost by TCRIGHT */
+		putc(' ', shout);
+	    if (tccan(TCSAVECURSOR)
+	     && tcmultout(TCRIGHT, TCMULTRIGHT, columns - 3)) {
+		putc(' ', shout);
+		putc(' ', shout);
+		tcout(TCSAVECURSOR);
+		tcout(TCBACKSPACE);
+		tcout(TCBACKSPACE);
+		if (tccan(TCCLEAREOL))
+		    tcout(TCCLEAREOL);
+		else
+		    tcmultout(TCDEL, TCMULTDEL, 1);
+		tcout(TCRESTRCURSOR);
+	    } else
+		fprintf(shout, "%*s", (int)columns - 1, "");
+	}
 	putc('\r', shout);
+    }
     if (tmout)
 	alarm(tmout);
     zleactive = 1;