From 64bef388133a0ad239301e2230a2c62012c490b2 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 26 Dec 2018 20:39:04 +0530
Subject: [PATCH] macOS: Fix momentum scrolling continuing when changing the
 active window/tab

Fixes #1267
---
 docs/changelog.rst |  3 +++
 kitty/mouse.c      | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 60bbf531a..e2b3ecb6b 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -31,6 +31,9 @@ Changelog
 - Fix using the ``new_tab !neighbor`` action changing the order of the
   non-neighboring tabs (:iss:`1256`)
 
+- macOS: Fix momentum scrolling continuing when changing the active window/tab
+  (:iss:`1267`)
+
 
 0.13.1 [2018-12-06]
 ------------------------------
diff --git a/kitty/mouse.c b/kitty/mouse.c
index e3cdc3599..54ea72a9e 100644
--- a/kitty/mouse.c
+++ b/kitty/mouse.c
@@ -557,6 +557,7 @@ mouse_event(int button, int modifiers, int action) {
 void
 scroll_event(double UNUSED xoffset, double yoffset, int flags) {
     bool in_tab_bar;
+    static id_type window_for_momentum_scroll = 0;
     unsigned int window_idx = 0;
     Window *w = window_for_event(&window_idx, &in_tab_bar);
     if (!w && !in_tab_bar) {
@@ -571,6 +572,15 @@ scroll_event(double UNUSED xoffset, double yoffset, int flags) {
     int s;
     bool is_high_resolution = flags & 1;
     Screen *screen = w->render_data.screen;
+    int momentum_data = (flags > 1) & 3;
+    switch(momentum_data) {
+        case 1:
+            window_for_momentum_scroll = w->id; break;
+        case 2:
+            if (window_for_momentum_scroll != w->id) return;
+        case 3:
+            window_for_momentum_scroll = 0; break;
+    }
     if (is_high_resolution) {
         yoffset *= OPT(touch_scroll_multiplier);
         if (yoffset * global_state.callback_os_window->pending_scroll_pixels < 0) {