Correct implementation of extended frame synchronization

* src/xterm.c (handle_one_xevent): Use value provided in the
extended synchronization message as the current counter value.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 167e3a44d23..d3d8dc468cd 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -9139,7 +9139,11 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                         FRAME_X_OUTPUT (f)->sync_end_pending_p = true;
                       }
                     else if (event->xclient.data.l[4] == 1)
-                      FRAME_X_OUTPUT (f)->ext_sync_end_pending_p = true;
+                      {
+                        XSyncIntsToValue (&FRAME_X_OUTPUT (f)->current_extended_counter_value,
+                                          event->xclient.data.l[2], event->xclient.data.l[3]);
+                        FRAME_X_OUTPUT (f)->ext_sync_end_pending_p = true;
+                      }
 
                     *finish = X_EVENT_DROP;
                     goto done;