patch 9.1.0081: X11 mouse-scrolling stutters

Problem:  X11 mouse-scrolling stutters
          (Ron Aaron, after 9.1.0064)
Solution: Handle GDK_SCROLL_SMOOTH fractional distance events
          (lilydjwg)

I don't know why, but with GDK_SMOOTH_SCROLL_MASK we get wheel events as
GDK_SCROLL_SMOOTH. What's more, one wheel scroll is counted as 1.5
distance in Wayland but 1.0 in X11.

I failed to find any docs on gtk.org about this.

fixes: #13987
closes: #13991

Signed-off-by: lilydjwg <lilydjwg@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/gui_gtk_x11.c

@@ -2105,25 +2105,25 @@ scroll_event(GtkWidget *widget,
 #if GTK_CHECK_VERSION(3,4,0)
     if (event->direction == GDK_SCROLL_SMOOTH)
     {
-	while (acc_x > 1.0)
+	while (acc_x >= 1.0)
 	{ // right
 	    acc_x = MAX(0.0, acc_x - 1.0);
 	    gui_send_mouse_event(MOUSE_6, (int)event->x, (int)event->y,
 		    FALSE, vim_modifiers);
 	}
-	while (acc_x < -1.0)
+	while (acc_x <= -1.0)
 	{ // left
 	    acc_x = MIN(0.0, acc_x + 1.0);
 	    gui_send_mouse_event(MOUSE_7, (int)event->x, (int)event->y,
 		    FALSE, vim_modifiers);
 	}
-	while (acc_y > 1.0)
+	while (acc_y >= 1.0)
 	{ // down
 	    acc_y = MAX(0.0, acc_y - 1.0);
 	    gui_send_mouse_event(MOUSE_5, (int)event->x, (int)event->y,
 		    FALSE, vim_modifiers);
 	}
-	while (acc_y < -1.0)
+	while (acc_y <= -1.0)
 	{ // up
 	    acc_y = MIN(0.0, acc_y + 1.0);
 	    gui_send_mouse_event(MOUSE_4, (int)event->x, (int)event->y,

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    81,
 /**/
     80,
 /**/