master e359df4217: Fix more toolkit scroll bar window protection issues

[Po Lu]

branch: master
commit e359df4217a392bb3185ff7449656c0a8953a6f4
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix more toolkit scroll bar window protection issues
    
    * src/xterm.c (handle_one_xevent): Ignore outdated scroll bar
    events.
    (x_free_frame_resources): Clear protected windows and invalidate
    previous scroll bar events.
    * src/xterm.h (struct x_display_info): New field
    `first_valid_scroll_bar_req'.
---
 src/xterm.c | 18 ++++++++++++++++--
 src/xterm.h |  9 +++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/xterm.c b/src/xterm.c
index 6860ef2080..2d366e5511 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -18109,7 +18109,9 @@ handle_one_xevent (struct x_display_info *dpyinfo,
            /* Unprotect the first window to be sent in a
               ClientMessage event, since it is now on the stack and
               thereby subject to garbage collection.  */
-           x_unprotect_window_for_callback (dpyinfo);
+           if (event->xclient.serial
+               >= dpyinfo->first_valid_scroll_bar_req)
+             x_unprotect_window_for_callback (dpyinfo);
 
            *finish = X_EVENT_GOTO_OUT;
             goto done;
@@ -18121,7 +18123,9 @@ handle_one_xevent (struct x_display_info *dpyinfo,
            /* Unprotect the first window to be sent in a
               ClientMessage event, since it is now on the stack and
               thereby subject to garbage collection.  */
-           x_unprotect_window_for_callback (dpyinfo);
+           if (event->xclient.serial
+               >= dpyinfo->first_valid_scroll_bar_req)
+             x_unprotect_window_for_callback (dpyinfo);
 
            *finish = X_EVENT_GOTO_OUT;
             goto done;
@@ -27339,6 +27343,16 @@ x_free_frame_resources (struct frame *f)
 #if defined HAVE_XSYNCTRIGGERFENCE && !defined USE_GTK && defined 
HAVE_CLOCK_GETTIME
       x_sync_free_fences (f);
 #endif
+
+#ifdef USE_TOOLKIT_SCROLL_BARS
+      /* Since the frame was destroyed, we can no longer guarantee
+        that scroll bar events will be received.  Clear
+        protected_windows, and ignore any preceding scroll bar events
+        that happen to still be deliverable.  */
+      dpyinfo->n_protected_windows = 0;
+      dpyinfo->first_valid_scroll_bar_req
+       = XNextRequest (dpyinfo->display);
+#endif
     }
 
 #ifdef HAVE_GTK3
diff --git a/src/xterm.h b/src/xterm.h
index d6ff15e40f..d1671621c7 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -839,6 +839,15 @@ struct x_display_info
      server_time_monotonic_p will be true).  */
   int_fast64_t server_time_offset;
 #endif
+
+#if defined USE_TOOLKIT_SCROLL_BARS
+  /* Serial number of the first scroll bar event to start listening
+     to.  This is necessary because protected_windows is display
+     local, but the destruction of a frame's edit window may cause
+     event windows to vanish before they are delivered, leading to
+     windows remaining protected indefinitely.  */
+  unsigned long first_valid_scroll_bar_req;
+#endif
 };
 
 #ifdef HAVE_X_I18N