new feature: option --stateflags to show some states in top-right corner

With --stateflags (short form: -%) or 'set stateflags', nano reserves
the righthand end of the title bar not for showing "Modified" but for
showing the state of auto-indentation (I), the mark (M), the breaking
of long lines (L), macro recording (R), and softwrapping (S).

When the buffer is modified, this is indicated with a star (*) after
the file name (shown in the center of the title bar).

This fulfills https://savannah.gnu.org/bugs/?57953.
Requested-by: Sébastien Desreux <seb@h-k.fr>

src/definitions.h

@@ -541,7 +541,8 @@ enum
 	JUMPY_SCROLLING,
 	EMPTY_LINE,
 	INDICATOR,
-	BOOKSTYLE
+	BOOKSTYLE,
+	STATEFLAGS
 };
 
 /* Flags for the menus in which a given function should be present. */

src/nano.c

@@ -497,6 +497,7 @@ void usage(void)
 #ifndef NANO_TINY
 	/* TRANSLATORS: The next forty or so strings are option descriptions
 	 * for the --help output.  Try to keep them at most 40 characters. */
+	print_opt("-%", "--stateflags", N_("Show some states on the title bar"));
 	print_opt("-A", "--smarthome", N_("Enable smart home key"));
 	if (!ISSET(RESTRICTED)) {
 		print_opt("-B", "--backup", N_("Save backups of existing files"));
@@ -1113,6 +1114,10 @@ void do_toggle(int flag)
 #endif
 	}
 
+	if (ISSET(STATEFLAGS) && (flag == AUTOINDENT ||
+						flag == BREAK_LONG_LINES || flag == SOFTWRAP))
+		titlebar(NULL);
+
 	enabled = ISSET(flag);
 
 	if (flag == NO_HELP || flag == NO_SYNTAX)
@@ -1528,6 +1533,9 @@ void process_a_keystroke(void)
 		/* The input buffer for actual characters. */
 	static size_t depth = 0;
 		/* The length of the input buffer. */
+#ifndef NANO_TINY
+	linestruct *was_mark = openfile->mark;
+#endif
 	static bool give_a_hint = TRUE;
 	const keystruct *shortcut;
 
@@ -1667,6 +1675,9 @@ void process_a_keystroke(void)
 #ifndef NANO_TINY
 	if (bracketed_paste)
 		suck_up_input_and_paste_it();
+
+	if (ISSET(STATEFLAGS) && openfile->mark != was_mark)
+		titlebar(NULL);
 #endif
 }
 
@@ -1750,6 +1761,7 @@ int main(int argc, char **argv)
 		{"nohelp", 0, NULL, 'x'},
 		{"suspendable", 0, NULL, 'z'},
 #ifndef NANO_TINY
+		{"stateflags", 0, NULL, '%'},
 		{"smarthome", 0, NULL, 'A'},
 		{"backup", 0, NULL, 'B'},
 		{"backupdir", 1, NULL, 'C'},
@@ -1829,10 +1841,13 @@ int main(int argc, char **argv)
 	if (*(tail(argv[0])) == 'r')
 		SET(RESTRICTED);
 
-	while ((optchr = getopt_long(argc, argv, "ABC:DEFGHIJ:KLMNOPQ:RST:UVWX:Y:Z"
+	while ((optchr = getopt_long(argc, argv, "%ABC:DEFGHIJ:KLMNOPQ:RST:UVWX:Y:Z"
 				"abcdef:ghijklmno:pqr:s:tuvwxyz$", long_options, NULL)) != -1) {
 		switch (optchr) {
 #ifndef NANO_TINY
+			case '%':
+				SET(STATEFLAGS);
+				break;
 			case 'A':
 				SET(SMART_HOME);
 				break;

src/rcfile.c

@@ -114,6 +114,7 @@ static const rcoption rcopts[] = {
 	{"smarthome", SMART_HOME},
 	{"smooth", SMOOTH_SCROLL},  /* Deprecated; remove in 2021. */
 	{"softwrap", SOFTWRAP},
+	{"stateflags", STATEFLAGS},
 	{"tabstospaces", TABS_TO_SPACES},
 	{"trimblanks", TRIM_BLANKS},
 	{"unix", MAKE_IT_UNIX},

src/winio.c

@@ -97,6 +97,9 @@ void record_macro(void)
 		snip_last_keystroke();
 		statusbar(_("Stopped recording"));
 	}
+
+	if (ISSET(STATEFLAGS))
+		titlebar(NULL);
 }
 
 /* Copy the stored sequence of codes into the regular key buffer,
@@ -1973,6 +1976,9 @@ void titlebar(const char *path)
 		else
 			path = openfile->filename;
 
+		if (ISSET(STATEFLAGS) && !ISSET(VIEW_MODE))
+			state = "+.xxxxx";
+		else
 		if (openfile->modified)
 			state = _("Modified");
 		else if (ISSET(VIEW_MODE))
@@ -2036,11 +2042,26 @@ void titlebar(const char *path)
 		free(caption);
 	}
 
+	/* When requested, show on the title bar the state of three options and
+	 * the state of the mark and whether a macro is being recorded. */
+	if (ISSET(STATEFLAGS) && !ISSET(VIEW_MODE)) {
+		if (COLS > 1)
+			waddstr(topwin, openfile->modified ? " *" : "  ");
+		if (statelen < COLS) {
+			wmove(topwin, 0, COLS + 2 - statelen);
+			waddstr(topwin, ISSET(AUTOINDENT) ? "I" : " ");
+			waddstr(topwin, openfile->mark ? "M" : " ");
+			waddstr(topwin, ISSET(BREAK_LONG_LINES) ? "L" : " ");
+			waddstr(topwin, recording ? "R" : " ");
+			waddstr(topwin, ISSET(SOFTWRAP) ? "S" : " ");
+		}
+	} else {
 	/* Right-align the state if there's room; otherwise, trim it. */
 	if (statelen > 0 && statelen <= COLS)
 		mvwaddstr(topwin, 0, COLS - statelen, state);
 	else if (statelen > 0)
 		mvwaddnstr(topwin, 0, 0, state, actual_x(state, COLS));
+	}
 
 	wattroff(topwin, interface_color_pair[TITLE_BAR]);