[mutter] window: Handle TOUCH_BEGIN events separately during grab ops

[Marge Bot <marge-bot src gnome org>]

commit ef1b1018210a10a54d55ca0415e18461743a4dc0
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Thu Mar 14 10:49:19 2019 +0100

    window: Handle TOUCH_BEGIN events separately during grab ops
    
    Handle the case of a TOUCH_BEGIN event during window dragging separately
    instead of treating it like a TOUCH_UPDATE event: Simply return TRUE to
    make Clutter stop event propagation if it's the pointer emulating
    sequence and let Clutter propagate the event if it isn't.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/427>

 src/core/window.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index b68dcb2b69..47fff926e8 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -6497,6 +6497,12 @@ meta_window_handle_mouse_grab_op_event  (MetaWindow         *window,
 
   switch (event->type)
     {
+    case CLUTTER_TOUCH_BEGIN:
+      if (!meta_display_is_pointer_emulating_sequence (window->display, sequence))
+        return FALSE;
+
+      return TRUE;
+
     case CLUTTER_BUTTON_PRESS:
       {
         ClutterModifierType grab_mods = meta_display_get_compositor_modifiers (window->display);
@@ -6529,12 +6535,6 @@ meta_window_handle_mouse_grab_op_event  (MetaWindow         *window,
 
       return TRUE;
 
-    case CLUTTER_TOUCH_BEGIN:
-      /* This will only catch the keybinding and menu cases, just deal with this
-       * like a CLUTTER_TOUCH_UPDATE rather than a CLUTTER_BUTTON_PRESS, and
-       * wait until CLUTTER_TOUCH_END to undo the grab, just so the window
-       * doesn't warp below the finger and remain there.
-       */
     case CLUTTER_TOUCH_UPDATE:
       if (!meta_display_is_pointer_emulating_sequence (window->display, sequence))
         return FALSE;