Remove `scrollback` feature.

Squashed commit of the following:

commit aab2886e03e4a239aca6e013454864734b669f76
Author: Mateja <mail@matejamaric.com>
Date:   Sun Apr 11 16:10:22 2021 +0200

    Revert "Applied first `scrollback` patch."

    This reverts commit e2a49699774c0256f6c745c55f42c7c56a5e0d95.

commit 16f52eb7d91426aec2f92dd46d90031402567889
Author: Mateja <mail@matejamaric.com>
Date:   Sun Apr 11 16:08:30 2021 +0200

    Revert "Applied second `scrollback` patch."

    This reverts commit 09f652d8aff93ba8b7e96d07a58c1aa520f44a2f.

commit 9b55f3b7607c44d1c26353d3e9d6d23d59758195
Author: Mateja <mail@matejamaric.com>
Date:   Sun Apr 11 16:08:18 2021 +0200

    Revert "Applied third `scrollback` patch."

    This reverts commit c2131a689c5b83d2f5015f5afdce5ab3bc58e734.

commit 0a2f1c12ae3e9134df6b92f1a9443369f8fac591
Author: Mateja <mail@matejamaric.com>
Date:   Sun Apr 11 16:06:48 2021 +0200

    Revert "Add `scrollback` to README."

    This reverts commit 1c354fe11695ffa5d00bcc86ecb84c7edb1fd7b6.

5 files changed, 27 insertions, 117 deletions

diff --git a/README.md b/README.md
index 70950a8..954abdb 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,6 @@ This is my fork of [st][stterm] terminal with following patches applied:
 - boxdraw
 - newterm
 - desktopentry
-- scrollback (with mouse)
 - clipboard
 - externalpipe (for URLs)
 - xresources
diff --git a/config.def.h b/config.def.h
index b8e4a2c..15a269f 100644
--- a/config.def.h
+++ b/config.def.h
@@ -226,8 +226,6 @@ ResourcePref resources[] = {
  */
 static MouseShortcut mshortcuts[] = {
 	/* mask                 button   function        argument       release */
-	{ XK_ANY_MOD,           Button4, kscrollup,      {.i = 1},      0, /* !alt */ -1 },
-	{ XK_ANY_MOD,           Button5, kscrolldown,    {.i = 1},      0, /* !alt */ -1 },
 	{ XK_ANY_MOD,           Button2, selpaste,       {.i = 0},      1 },
 	{ ShiftMask,            Button4, ttysend,        {.s = "\033[5;2~"} },
 	{ XK_ANY_MOD,           Button4, ttysend,        {.s = "\031"} },
@@ -257,14 +255,8 @@ static Shortcut shortcuts[] = {
 	{ ShiftMask,            XK_Insert,      selpaste,       {.i =  0} },
 	{ TERMMOD,              XK_Num_Lock,    numlock,        {.i =  0} },
 	{ TERMMOD,              XK_Return,      newterm,        {.i =  0} },
-	{ ShiftMask,            XK_Page_Up,     kscrollup,      {.i = -1} },
-	{ ShiftMask,            XK_Page_Down,   kscrolldown,    {.i = -1} },
 	{ MODKEY,               XK_l,           externalpipe,   {.v = openurlcmd } },
 	{ MODKEY,               XK_y,           externalpipe,   {.v = copyurlcmd } },
-	{ MODKEY,               XK_k,           kscrollup,      {.i =  1} },
-	{ MODKEY,               XK_j,           kscrolldown,    {.i =  1} },
-	{ MODKEY,               XK_u,           kscrollup,      {.i = -1} },
-	{ MODKEY,               XK_d,           kscrolldown,    {.i = -1} },
 };
 
 /*
diff --git a/st.c b/st.c
index 0bb8a2e..7a99bc1 100644
--- a/st.c
+++ b/st.c
@@ -35,7 +35,6 @@
 #define ESC_ARG_SIZ   16
 #define STR_BUF_SIZ   ESC_BUF_SIZ
 #define STR_ARG_SIZ   ESC_ARG_SIZ
-#define HISTSIZE      2000
 
 /* macros */
 #define IS_SET(flag)		((term.mode & (flag)) != 0)
@@ -43,9 +42,6 @@
 #define ISCONTROLC1(c)		(BETWEEN(c, 0x80, 0x9f))
 #define ISCONTROL(c)		(ISCONTROLC0(c) || ISCONTROLC1(c))
 #define ISDELIM(u)		(u && wcschr(worddelimiters, u))
-#define TLINE(y)		((y) < term.scr ? term.hist[((y) + term.histi - \
-				term.scr + HISTSIZE + 1) % HISTSIZE] : \
-				term.line[(y) - term.scr])
 
 enum term_mode {
 	MODE_WRAP        = 1 << 0,
@@ -119,9 +115,6 @@ typedef struct {
 	int col;      /* nb col */
 	Line *line;   /* screen */
 	Line *alt;    /* alternate screen */
-	Line hist[HISTSIZE]; /* history buffer */
-	int histi;    /* history index */
-	int scr;      /* scroll back */
 	int *dirty;   /* dirtyness of lines */
 	TCursor c;    /* cursor */
 	int ocx;      /* old cursor col */
@@ -192,8 +185,8 @@ static void tnewline(int);
 static void tputtab(int);
 static void tputc(Rune);
 static void treset(void);
-static void tscrollup(int, int, int);
-static void tscrolldown(int, int, int);
+static void tscrollup(int, int);
+static void tscrolldown(int, int);
 static void tsetattr(int *, int);
 static void tsetchar(Rune, Glyph *, int, int);
 static void tsetdirt(int, int);
@@ -422,10 +415,10 @@ tlinelen(int y)
 {
 	int i = term.col;
 
-	if (TLINE(y)[i - 1].mode & ATTR_WRAP)
+	if (term.line[y][i - 1].mode & ATTR_WRAP)
 		return i;
 
-	while (i > 0 && TLINE(y)[i - 1].u == ' ')
+	while (i > 0 && term.line[y][i - 1].u == ' ')
 		--i;
 
 	return i;
@@ -534,7 +527,7 @@ selsnap(int *x, int *y, int direction)
 		 * Snap around if the word wraps around at the end or
 		 * beginning of a line.
 		 */
-		prevgp = &TLINE(*y)[*x];
+		prevgp = &term.line[*y][*x];
 		prevdelim = ISDELIM(prevgp->u);
 		for (;;) {
 			newx = *x + direction;
@@ -549,14 +542,14 @@ selsnap(int *x, int *y, int direction)
 					yt = *y, xt = *x;
 				else
 					yt = newy, xt = newx;
-				if (!(TLINE(yt)[xt].mode & ATTR_WRAP))
+				if (!(term.line[yt][xt].mode & ATTR_WRAP))
 					break;
 			}
 
 			if (newx >= tlinelen(newy))
 				break;
 
-			gp = &TLINE(newy)[newx];
+			gp = &term.line[newy][newx];
 			delim = ISDELIM(gp->u);
 			if (!(gp->mode & ATTR_WDUMMY) && (delim != prevdelim
 					|| (delim && gp->u != prevgp->u)))
@@ -577,14 +570,14 @@ selsnap(int *x, int *y, int direction)
 		*x = (direction < 0) ? 0 : term.col - 1;
 		if (direction < 0) {
 			for (; *y > 0; *y += direction) {
-				if (!(TLINE(*y-1)[term.col-1].mode
+				if (!(term.line[*y-1][term.col-1].mode
 						& ATTR_WRAP)) {
 					break;
 				}
 			}
 		} else if (direction > 0) {
 			for (; *y < term.row-1; *y += direction) {
-				if (!(TLINE(*y)[term.col-1].mode
+				if (!(term.line[*y][term.col-1].mode
 						& ATTR_WRAP)) {
 					break;
 				}
@@ -615,13 +608,13 @@ getsel(void)
 		}
 
 		if (sel.type == SEL_RECTANGULAR) {
-			gp = &TLINE(y)[sel.nb.x];
+			gp = &term.line[y][sel.nb.x];
 			lastx = sel.ne.x;
 		} else {
-			gp = &TLINE(y)[sel.nb.y == y ? sel.nb.x : 0];
+			gp = &term.line[y][sel.nb.y == y ? sel.nb.x : 0];
 			lastx = (sel.ne.y == y) ? sel.ne.x : term.col-1;
 		}
-		last = &TLINE(y)[MIN(lastx, linelen-1)];
+		last = &term.line[y][MIN(lastx, linelen-1)];
 		while (last >= gp && last->u == ' ')
 			--last;
 
@@ -862,9 +855,6 @@ void
 ttywrite(const char *s, size_t n, int may_echo)
 {
 	const char *next;
-	Arg arg = (Arg) { .i = term.scr };
-
-	kscrolldown(&arg);
 
 	if (may_echo && IS_SET(MODE_ECHO))
 		twrite(s, n, 1);
@@ -1064,11 +1054,6 @@ tnew(int col, int row)
 	treset();
 }
 
-int tisaltscr(void)
-{
-	return IS_SET(MODE_ALTSCREEN);
-}
-
 void
 tswapscreen(void)
 {
@@ -1101,53 +1086,13 @@ static char *getcwd_by_pid(pid_t pid) {
 }
 
 void
-kscrolldown(const Arg* a)
-{
-	int n = a->i;
-
-	if (n < 0)
-		n = term.row + n;
-
-	if (n > term.scr)
-		n = term.scr;
-
-	if (term.scr > 0) {
-		term.scr -= n;
-		selscroll(0, -n);
-		tfulldirt();
-	}
-}
-
-void
-kscrollup(const Arg* a)
-{
-	int n = a->i;
-
-	if (n < 0)
-		n = term.row + n;
-
-	if (term.scr <= HISTSIZE-n) {
-		term.scr += n;
-		selscroll(0, n);
-		tfulldirt();
-	}
-}
-
-void
-tscrolldown(int orig, int n, int copyhist)
+tscrolldown(int orig, int n)
 {
 	int i;
 	Line temp;
 
 	LIMIT(n, 0, term.bot-orig+1);
 
-	if (copyhist) {
-		term.histi = (term.histi - 1 + HISTSIZE) % HISTSIZE;
-		temp = term.hist[term.histi];
-		term.hist[term.histi] = term.line[term.bot];
-		term.line[term.bot] = temp;
-	}
-
 	tsetdirt(orig, term.bot-n);
 	tclearregion(0, term.bot-n+1, term.col-1, term.bot);
 
@@ -1157,28 +1102,17 @@ tscrolldown(int orig, int n, int copyhist)
 		term.line[i-n] = temp;
 	}
 
-	if (term.scr == 0)
-		selscroll(orig, n);
+	selscroll(orig, n);
 }
 
 void
-tscrollup(int orig, int n, int copyhist)
+tscrollup(int orig, int n)
 {
 	int i;
 	Line temp;
 
 	LIMIT(n, 0, term.bot-orig+1);
 
-	if (copyhist) {
-		term.histi = (term.histi + 1) % HISTSIZE;
-		temp = term.hist[term.histi];
-		term.hist[term.histi] = term.line[orig];
-		term.line[orig] = temp;
-	}
-
-	if (term.scr > 0 && term.scr < HISTSIZE)
-		term.scr = MIN(term.scr + n, HISTSIZE-1);
-
 	tclearregion(0, orig, term.col-1, orig+n-1);
 	tsetdirt(orig+n, term.bot);
 
@@ -1188,8 +1122,7 @@ tscrollup(int orig, int n, int copyhist)
 		term.line[i+n] = temp;
 	}
 
-	if (term.scr == 0)
-		selscroll(orig, -n);
+	selscroll(orig, -n);
 }
 
 void
@@ -1218,7 +1151,7 @@ tnewline(int first_col)
 	int y = term.c.y;
 
 	if (y == term.bot) {
-		tscrollup(term.top, 1, 1);
+		tscrollup(term.top, 1);
 	} else {
 		y++;
 	}
@@ -1386,14 +1319,14 @@ void
 tinsertblankline(int n)
 {
 	if (BETWEEN(term.c.y, term.top, term.bot))
-		tscrolldown(term.c.y, n, 0);
+		tscrolldown(term.c.y, n);
 }
 
 void
 tdeleteline(int n)
 {
 	if (BETWEEN(term.c.y, term.top, term.bot))
-		tscrollup(term.c.y, n, 0);
+		tscrollup(term.c.y, n);
 }
 
 int32_t
@@ -1830,11 +1763,11 @@ csihandle(void)
 		break;
 	case 'S': /* SU -- Scroll <n> line up */
 		DEFAULT(csiescseq.arg[0], 1);
-		tscrollup(term.top, csiescseq.arg[0], 0);
+		tscrollup(term.top, csiescseq.arg[0]);
 		break;
 	case 'T': /* SD -- Scroll <n> line down */
 		DEFAULT(csiescseq.arg[0], 1);
-		tscrolldown(term.top, csiescseq.arg[0], 0);
+		tscrolldown(term.top, csiescseq.arg[0]);
 		break;
 	case 'L': /* IL -- Insert <n> blank lines */
 		DEFAULT(csiescseq.arg[0], 1);
@@ -2391,7 +2324,7 @@ eschandle(uchar ascii)
 		return 0;
 	case 'D': /* IND -- Linefeed */
 		if (term.c.y == term.bot) {
-			tscrollup(term.top, 1, 1);
+			tscrollup(term.top, 1);
 		} else {
 			tmoveto(term.c.x, term.c.y+1);
 		}
@@ -2404,7 +2337,7 @@ eschandle(uchar ascii)
 		break;
 	case 'M': /* RI -- Reverse index */
 		if (term.c.y == term.top) {
-			tscrolldown(term.top, 1, 1);
+			tscrolldown(term.top, 1);
 		} else {
 			tmoveto(term.c.x, term.c.y-1);
 		}
@@ -2614,7 +2547,7 @@ twrite(const char *buf, int buflen, int show_ctrl)
 void
 tresize(int col, int row)
 {
-	int i, j;
+	int i;
 	int minrow = MIN(row, term.row);
 	int mincol = MIN(col, term.col);
 	int *bp;
@@ -2651,14 +2584,6 @@ tresize(int col, int row)
 	term.dirty = xrealloc(term.dirty, row * sizeof(*term.dirty));
 	term.tabs = xrealloc(term.tabs, col * sizeof(*term.tabs));
 
-	for (i = 0; i < HISTSIZE; i++) {
-		term.hist[i] = xrealloc(term.hist[i], col * sizeof(Glyph));
-		for (j = mincol; j < col; j++) {
-			term.hist[i][j] = term.c.attr;
-			term.hist[i][j].u = ' ';
-		}
-	}
-
 	/* resize each row to new width, zero-pad if needed */
 	for (i = 0; i < minrow; i++) {
 		term.line[i] = xrealloc(term.line[i], col * sizeof(Glyph));
@@ -2717,7 +2642,7 @@ drawregion(int x1, int y1, int x2, int y2)
 			continue;
 
 		term.dirty[y] = 0;
-		xdrawline(TLINE(y), x1, y, x2);
+		xdrawline(term.line[y], x1, y, x2);
 	}
 }
 
@@ -2738,9 +2663,8 @@ draw(void)
 		cx--;
 
 	drawregion(0, 0, term.col, term.row);
-	if (term.scr == 0)
-		xdrawcursor(cx, term.c.y, term.line[term.c.y][cx],
-				term.ocx, term.ocy, term.line[term.ocy][term.ocx]);
+	xdrawcursor(cx, term.c.y, term.line[term.c.y][cx],
+			term.ocx, term.ocy, term.line[term.ocy][term.ocx]);
 	term.ocx = cx;
 	term.ocy = term.c.y;
 	xfinishdraw();
diff --git a/st.h b/st.h
index b41e6c0..315fb02 100644
--- a/st.h
+++ b/st.h
@@ -83,8 +83,6 @@ void redraw(void);
 void draw(void);
 
 void externalpipe(const Arg *);
-void kscrolldown(const Arg *);
-void kscrollup(const Arg *);
 void newterm(const Arg *);
 void printscreen(const Arg *);
 void printsel(const Arg *);
@@ -92,7 +90,6 @@ void sendbreak(const Arg *);
 void toggleprinter(const Arg *);
 
 int tattrset(int);
-int tisaltscr(void);
 void tnew(int, int);
 void tresize(int, int);
 void tsetdirtattr(int);
diff --git a/x.c b/x.c
index 39bd8d5..05cdc7b 100644
--- a/x.c
+++ b/x.c
@@ -35,7 +35,6 @@ typedef struct {
 	void (*func)(const Arg *);
 	const Arg arg;
 	uint  release;
-	int  altscrn;  /* 0: don't care, -1: not alt screen, 1: alt screen */
 } MouseShortcut;
 
 typedef struct {
@@ -463,7 +462,6 @@ mouseaction(XEvent *e, uint release)
 	for (ms = mshortcuts; ms < mshortcuts + LEN(mshortcuts); ms++) {
 		if (ms->release == release &&
 		    ms->button == e->xbutton.button &&
-		    (!ms->altscrn || (ms->altscrn == (tisaltscr() ? 1 : -1))) &&
 		    (match(ms->mod, state) ||  /* exact or forced */
 		     match(ms->mod, state & ~forcemousemod))) {
 			ms->func(&(ms->arg));