Add scroll

This reverts commit e8392b282c.

There is currently a bug in older ncurses versions (like on OpenBSD) where a
fix for a bug with REP is not backported yet. Most likely in tty/tty_update.c:

Noticed while using lynx (which uses ncurses/curses).
To reproduce using lynx: echo "Z0000000" | lynx -stdin

or using the program:

int
main(void)
{
	WINDOW *win;
	win = initscr();

	printw("Z0000000");

	refresh();

	sleep(5);

	return 0;
}

This prints "ZZZZZZZ" (incorrectly).

config.def.h

@@ -19,7 +19,7 @@ static int borderpx = 2;
 static char *shell = "/bin/sh";
 char *utmp = NULL;
 /* scroll program: to enable use a string like "scroll" */
-char *scroll = NULL;
+char *scroll = "scroll";
 char *stty_args = "stty raw pass8 nl -echo -iexten -cstopb 38400";
 
 /* identification sequence returned in DA and DECID */
@@ -171,7 +171,9 @@ static uint forcemousemod = ShiftMask;
 static MouseShortcut mshortcuts[] = {
 	/* mask                 button   function        argument       release */
 	{ XK_ANY_MOD,           Button2, selpaste,       {.i = 0},      1 },
+	{ ShiftMask,            Button4, ttysend,        {.s = "\033[5;2~"} },
 	{ XK_ANY_MOD,           Button4, ttysend,        {.s = "\031"} },
+	{ ShiftMask,            Button5, ttysend,        {.s = "\033[6;2~"} },
 	{ XK_ANY_MOD,           Button5, ttysend,        {.s = "\005"} },
 };
 

st.c

@@ -1106,28 +1106,18 @@ selscroll(int orig, int n)
 	if (sel.ob.x == -1)
 		return;
 
-	if (BETWEEN(sel.ob.y, orig, term.bot) || BETWEEN(sel.oe.y, orig, term.bot)) {
-		if ((sel.ob.y += n) > term.bot || (sel.oe.y += n) < term.top) {
+	if (BETWEEN(sel.nb.y, orig, term.bot) != BETWEEN(sel.ne.y, orig, term.bot)) {
+		selclear();
+	} else if (BETWEEN(sel.nb.y, orig, term.bot)) {
+		sel.ob.y += n;
+		sel.oe.y += n;
+		if (sel.ob.y < term.top || sel.ob.y > term.bot ||
+		    sel.oe.y < term.top || sel.oe.y > term.bot) {
 			selclear();
-			return;
-		}
-		if (sel.type == SEL_RECTANGULAR) {
-			if (sel.ob.y < term.top)
-				sel.ob.y = term.top;
-			if (sel.oe.y > term.bot)
-				sel.oe.y = term.bot;
 		} else {
-			if (sel.ob.y < term.top) {
-				sel.ob.y = term.top;
-				sel.ob.x = 0;
-			}
-			if (sel.oe.y > term.bot) {
-				sel.oe.y = term.bot;
-				sel.oe.x = term.col;
-			}
-		}
 			selnormalize();
 		}
+	}
 }
 
 void

st.info

@@ -158,6 +158,7 @@ st-mono| simpleterm monocolor,
 	rc=\E8,
 	rev=\E[7m,
 	ri=\EM,
+	rin=\E[%p1%dT,
 	ritm=\E[23m,
 	rmacs=\E(B,
 	rmcup=\E[?1049l,