[PATCH] acme: implement 9front scrolling

[kvik@a-b.xyz]

This does away with one-line scrolling and implements scroll wheel
actions as seen in rio and sam.

It makes sense (to me) to unify scrolling behaviour across GUI programs,
but it is understandable that long-time acme users may feel otherwise.

Plaese feel invited to complain if this bugs you.

diff -r 35459627f401 sys/src/cmd/acme/acme.c
--- a/sys/src/cmd/acme/acme.c	Wed May 13 18:50:01 2020 -0700
+++ b/sys/src/cmd/acme/acme.c	Thu May 14 13:24:28 2020 +0200
@@ -506,8 +506,13 @@
 				but = 2;
 			else if(m.buttons == 4)
 				but = 3;
+			else if(m.buttons == 8)
+				but = 4;
+			else if(m.buttons == 16)
+				but = 5;
 			barttext = t;
-			if(t->what==Body && ptinrect(m.xy, t->scrollr)){
+			if(t->what==Body && w != nil
+			&& (ptinrect(m.xy, t->scrollr) || (m.buttons & (8|16)))){
 				if(but){
 					winlock(w, 'M');
 					t->eq0 = ~0;
@@ -516,18 +521,6 @@
 				}
 				goto Continue;
 			}
-			/* scroll buttons, wheels, etc. */
-			if(t->what==Body && w != nil && (m.buttons & (8|16))){
-				if(m.buttons & 8)
-					but = Kscrolloneup;
-				else
-					but = Kscrollonedown;
-				winlock(w, 'M');
-				t->eq0 = ~0;
-				texttype(t, but);
-				winunlock(w);
-				goto Continue;
-			}
 			if(ptinrect(m.xy, t->scrollr)){
 				if(but){
 					if(t->what == Columntag)
diff -r 35459627f401 sys/src/cmd/acme/scrl.c
--- a/sys/src/cmd/acme/scrl.c	Wed May 13 18:50:01 2020 -0700
+++ b/sys/src/cmd/acme/scrl.c	Thu May 14 13:24:28 2020 +0200
@@ -132,7 +132,7 @@
 			readmouse(mousectl);
 			continue;
 		}
-		if(but == 1)
+		if(but == 1 || but == 4)
 			p0 = textbacknl(t, t->org, (my-s.min.y)/t->font->height);
 		else
 			p0 = t->org+frcharofpt(t, Pt(s.max.x, my));
@@ -140,7 +140,7 @@
 			textsetorigin(t, p0, TRUE);
 		oldp0 = p0;
 		/* debounce */
-		if(first){
+		if(first && but < 4){
 			flushimage(display, 1);
 			sleep(200);
 			nbrecv(mousectl->c, &mousectl->Mouse);