support CSI escape seq 22 and 23

patch from https://st.suckless.org/patches/csi_22_23/st-csi_22_23-0.8.5.diff

co-authored-by: wael <40663@protonmail.com>

st.c

@@ -1864,6 +1864,33 @@ csihandle(void)
 			goto unknown;
 		}
 		break;
+	case 't': /* title stack operations */
+		switch (csiescseq.arg[0]) {
+		case 22: /* push current title on stack */
+			switch (csiescseq.arg[1]) {
+			case 0:
+			case 1:
+			case 2:
+				xpushtitle();
+				break;
+			default:
+				goto unknown;
+			}
+			break;
+		case 23: /* pop last title from stack */
+			switch (csiescseq.arg[1]) {
+			case 0:
+			case 1:
+			case 2:
+				xsettitle(NULL, 1);
+				break;
+			default:
+				goto unknown;
+			}
+			break;
+		default:
+			goto unknown;
+		}
 	}
 }
 
@@ -1942,7 +1969,7 @@ strhandle(void)
 		switch (par) {
 		case 0:
 			if (narg > 1) {
-				xsettitle(strescseq.args[1]);
+				xsettitle(strescseq.args[1], 0);
 				xseticontitle(strescseq.args[1]);
 			}
 			return;
@@ -1952,7 +1979,7 @@ strhandle(void)
 			return;
 		case 2:
 			if (narg > 1)
-				xsettitle(strescseq.args[1]);
+				xsettitle(strescseq.args[1], 0);
 			return;
 		case 52:
 			if (narg > 2 && allowwindowops) {
@@ -2007,7 +2034,7 @@ strhandle(void)
 		}
 		break;
 	case 'k': /* old title set compatibility */
-		xsettitle(strescseq.args[0]);
+		xsettitle(strescseq.args[0], 0);
 		return;
 	case 'P': /* DCS -- Device Control String */
 	case '_': /* APC -- Application Program Command */
@@ -2379,6 +2406,7 @@ eschandle(uchar ascii)
 		break;
 	case 'c': /* RIS -- Reset to initial state */
 		treset();
+		xfreetitlestack();
 		resettitle();
 		xloadcols();
 		break;
@@ -2673,7 +2701,7 @@ tresize(int col, int row)
 void
 resettitle(void)
 {
-	xsettitle(NULL);
+	xsettitle(NULL, 0);
 }
 
 void

st.info

@@ -161,7 +161,7 @@ st-mono| simpleterm monocolor,
 	rin=\E[%p1%dT,
 	ritm=\E[23m,
 	rmacs=\E(B,
-	rmcup=\E[?1049l,
+	rmcup=\E[?1049l\E[23;0;0t,
 	rmir=\E[4l,
 	rmkx=\E[?1l\E>,
 	rmso=\E[27m,
@@ -172,7 +172,7 @@ st-mono| simpleterm monocolor,
 	sitm=\E[3m,
 	sgr0=\E[0m,
 	smacs=\E(0,
-	smcup=\E[?1049h,
+	smcup=\E[?1049h\E[22;0;0t,
 	smir=\E[4h,
 	smkx=\E[?1h\E=,
 	smso=\E[7m,

win.h

@@ -32,7 +32,9 @@ void xloadcols(void);
 int xsetcolorname(int, const char *);
 int xgetcolor(int, unsigned char *, unsigned char *, unsigned char *);
 void xseticontitle(char *);
-void xsettitle(char *);
+void xfreetitlestack(void);
+void xsettitle(char *, int);
+void xpushtitle(void);
 int xsetcursor(int);
 void xsetmode(int, unsigned int);
 void xsetpointermotion(int);

x.c

@@ -66,6 +66,9 @@ extern void setupSegfaultHandler(void);
 /* config.h for applying patches and the configuration. */
 #include "config.h"
 
+/* size of title stack */
+#define TITLESTACKSIZE 8
+
 /* XEMBED messages */
 #define XEMBED_FOCUS_IN  4
 #define XEMBED_FOCUS_OUT 5
@@ -217,6 +220,8 @@ static DC dc;
 static XWindow xw;
 static XSelection xsel;
 static TermWindow win;
+static int tstki; /* title stack index */
+static char *titlestack[TITLESTACKSIZE]; /* title stack */
 
 /* Font Ring Cache */
 enum {
@@ -1623,10 +1628,30 @@ xseticontitle(char *p)
 }
 
 void
-xsettitle(char *p)
+xfreetitlestack(void)
+{
+	for (int i = 0; i < LEN(titlestack); i++) {
+		free(titlestack[i]);
+		titlestack[i] = NULL;
+	}
+}
+
+void
+xsettitle(char *p, int pop)
 {
 	XTextProperty prop;
-	DEFAULT(p, opt_title);
+
+	free(titlestack[tstki]);
+	if (pop) {
+		titlestack[tstki] = NULL;
+		tstki = (tstki - 1 + TITLESTACKSIZE) % TITLESTACKSIZE;
+		p = titlestack[tstki] ? titlestack[tstki] : opt_title;
+	} else if (p) {
+		titlestack[tstki] = xstrdup(p);
+	} else {
+		titlestack[tstki] = NULL;
+		p = opt_title;
+	}
 
 	if (Xutf8TextListToTextProperty(xw.dpy, &p, 1, XUTF8StringStyle,
 	                                &prop) != Success)
@@ -1636,6 +1661,16 @@ xsettitle(char *p)
 	XFree(prop.value);
 }
 
+void
+xpushtitle(void)
+{
+	int tstkin = (tstki + 1) % TITLESTACKSIZE;
+
+	free(titlestack[tstkin]);
+	titlestack[tstkin] = titlestack[tstki] ? xstrdup(titlestack[tstki]) : NULL;
+	tstki = tstkin;
+}
+
 int
 xstartdraw(void)
 {