use st-scrollback-mouse-altscreen-20190131-e23acb9

config.h

@@ -228,10 +228,8 @@ static MouseShortcut mshortcuts[] = {
 
 MouseKey mkeys[] = {
 	/* button               mask            function        argument */
-	{ Button4,              ShiftMask,      kscrollup,      {.i =  1} },
+	{ Button4,              XK_NO_MOD,      kscrollup,      {.i =  1} },
-	{ Button5,              ShiftMask,      kscrolldown,    {.i =  1} },
+	{ Button5,              XK_NO_MOD,      kscrolldown,    {.i =  1} },
-	{ Button4,              MODKEY,         kscrollup,      {.i =  1} },
-	{ Button5,              MODKEY,         kscrolldown,    {.i =  1} },
 	{ Button4,              TERMMOD,        zoom,           {.f =  +1} },
 	{ Button5,              TERMMOD,        zoom,           {.f =  -1} },
 };

st.c

@@ -1063,6 +1063,11 @@ tnew(int col, int row)
 	treset();
 }
 
+int tisaltscr(void)
+{
+	return IS_SET(MODE_ALTSCREEN);
+}
+
 void
 tswapscreen(void)
 {

st.h

@@ -104,6 +104,7 @@ 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);

x.c

@@ -442,6 +442,7 @@ bpress(XEvent *e)
 		return;
 	}
 
+	if (tisaltscr()) {
 		for (ms = mshortcuts; ms < mshortcuts + LEN(mshortcuts); ms++) {
 			if (e->xbutton.button == ms->b
 					&& match(ms->mask, e->xbutton.state)) {
@@ -449,6 +450,7 @@ bpress(XEvent *e)
 				return;
 			}
 		}
+	}
 
 	for (mk = mkeys; mk < mkeys + LEN(mkeys); mk++) {
 		if (e->xbutton.button == mk->b