wheel scrollback in normal, non-alt screen mode

patches from https://st.suckless.org/patches/scrollback/:

* https://st.suckless.org/patches/scrollback/st-scrollback-reflow-0.8.5.diff
* https://st.suckless.org/patches/scrollback/st-scrollback-mouse-20220127-2c5edf2.diff
* https://st.suckless.org/patches/scrollback/st-scrollback-mouse-altscreen-20220127-2c5edf2.diff

co-authored-by: Jochen Sprickerhof <st@jochen.sprickerhof.de>
co-authored-by: M Farkas-Dyck <strake888@gmail.com>
co-authored-by: Ivan Tham <pickfire@riseup.net>
co-authored-by: Ori Bernstein <ori@eigenstate.org>
co-authored-by: Matthias Schoth <mschoth@gmail.com>
co-authored-by: Laslo Hunhold <dev@frign.de>
co-authored-by: Paride Legovini <pl@ninthfloor.org>
co-authored-by: Lorenzo Bracco <devtry@riseup.net>
co-authored-by: Kamil Kleban <funmaker95@gmail.com>
co-authored-by: Avi Halachmi <avihpit@yahoo.com>
co-authored-by: Jacob Prosser <geriatricjacob@cumallover.me>
co-authored-by: Alexander Arkhipov <scm_2022@mineeyes.cyou>
co-authored-by: Ashish Kumar Yadav <ashishkumar.yadav@students.iiserpune.ac.in>

config.def.h

@@ -178,14 +178,18 @@ static uint forcemousemod = ShiftMask;
 /*
  * Internal mouse shortcuts.
  * Beware that overloading Button1 will disable the selection.
+ *
+ * alt screen - 0: don't care, -1: not alt screen, 1: alt screen
  */
 static MouseShortcut mshortcuts[] = {
-	/* mask                 button   function        argument       release */
+	/* mask                 button   function        argument           release    alt screen */
-	{ XK_ANY_MOD,           Button2, selpaste,       {.i = 0},      1 },
+	{ XK_ANY_MOD,           Button4, kscrollup,      {.i = 3},          0,         -1 },
-	{ ShiftMask,            Button4, ttysend,        {.s = "\033[5;2~"} },
+	{ XK_ANY_MOD,           Button5, kscrolldown,    {.i = 3},          0,         -1 },
-	{ XK_ANY_MOD,           Button4, ttysend,        {.s = "\031"} },
+	{ XK_ANY_MOD,           Button2, selpaste,       {.i = 0},          1             },
-	{ ShiftMask,            Button5, ttysend,        {.s = "\033[6;2~"} },
+	{ ShiftMask,            Button4, ttysend,        {.s = "\033[5;2~"}               },
-	{ XK_ANY_MOD,           Button5, ttysend,        {.s = "\005"} },
+	{ XK_ANY_MOD,           Button4, ttysend,        {.s = "\031"}                    },
+	{ ShiftMask,            Button5, ttysend,        {.s = "\033[6;2~"}               },
+	{ XK_ANY_MOD,           Button5, ttysend,        {.s = "\005"}                    },
 };
 
 /* Internal keyboard shortcuts. */

st.h

@@ -22,17 +22,19 @@
 
 enum glyph_attribute {
 	ATTR_NULL       = 0,
-	ATTR_BOLD       = 1 << 0,
+	ATTR_SET        = 1 << 0,
-	ATTR_FAINT      = 1 << 1,
+	ATTR_BOLD       = 1 << 1,
-	ATTR_ITALIC     = 1 << 2,
+	ATTR_FAINT      = 1 << 2,
-	ATTR_UNDERLINE  = 1 << 3,
+	ATTR_ITALIC     = 1 << 3,
-	ATTR_BLINK      = 1 << 4,
+	ATTR_UNDERLINE  = 1 << 4,
-	ATTR_REVERSE    = 1 << 5,
+	ATTR_BLINK      = 1 << 5,
-	ATTR_INVISIBLE  = 1 << 6,
+	ATTR_REVERSE    = 1 << 6,
-	ATTR_STRUCK     = 1 << 7,
+	ATTR_INVISIBLE  = 1 << 7,
-	ATTR_WRAP       = 1 << 8,
+	ATTR_STRUCK     = 1 << 8,
-	ATTR_WIDE       = 1 << 9,
+	ATTR_WRAP       = 1 << 9,
-	ATTR_WDUMMY     = 1 << 10,
+	ATTR_WIDE       = 1 << 10,
+	ATTR_WDUMMY     = 1 << 11,
+	ATTR_SELECTED   = 1 << 12,
 	ATTR_BOLD_FAINT = ATTR_BOLD | ATTR_FAINT,
 };
 
@@ -88,8 +90,10 @@ void printsel(const Arg *);
 void sendbreak(const Arg *);
 void toggleprinter(const Arg *);
 
+int tisaltscr(void);
 int tattrset(int);
 void tnew(int, int);
+int tisaltscreen(void);
 void tresize(int, int);
 void tsetdirtattr(int);
 void ttyhangup(void);

x.c

@@ -35,6 +35,7 @@ typedef struct {
 	void (*func)(const Arg *);
 	const Arg arg;
 	uint  release;
+	int  altscrn;
 } MouseShortcut;
 
 typedef struct {
@@ -457,6 +458,7 @@ 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));