From c2323f4397630349feb0b6afc3b09bd38d196fcc Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sat, 14 Oct 2017 11:52:27 -0400
Subject: [PATCH] Do not queue up mouse wheel scroll events while others are
 still processing

---
 src/gui/jtk/Jtk_event.cc | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/gui/jtk/Jtk_event.cc b/src/gui/jtk/Jtk_event.cc
index efd39e2..5d390ea 100644
--- a/src/gui/jtk/Jtk_event.cc
+++ b/src/gui/jtk/Jtk_event.cc
@@ -276,6 +276,15 @@ static bool ProcessXKeyReleaseEvent(XEvent * x_event, Jtk_Event * event)
     return false;
 }
 
+static Bool MatchButtonPress(Display * display, XEvent * event, XPointer arg)
+{
+    XEvent * match_event = (XEvent *)arg;
+    return (event->type == match_event->type) &&
+        (event->xbutton.window == match_event->xbutton.window) &&
+        (event->xbutton.state == match_event->xbutton.state) &&
+        (event->xbutton.button == match_event->xbutton.button);
+}
+
 /**
  * Process an X button press event.
  */
@@ -283,6 +292,15 @@ static bool ProcessXButtonPressEvent(XEvent * x_event, Jtk_Event * event)
 {
     event->type = JTK_EVENT_BUTTON_PRESS;
     event->button.button = x_event->xbutton.button;
+    /* If this is a mouse wheel scroll event, remove any following scroll
+     * events. */
+    if ((event->button.button == 4) || (event->button.button == 5))
+    {
+        XEvent remove_event;
+        while (XCheckIfEvent(g_display, &remove_event, MatchButtonPress, (XPointer)x_event) == True)
+        {
+        }
+    }
     return true;
 }