From: Po Lu <luangruo@yahoo.com>
Date: Sat, 4 Jun 2022 12:00:40 +0000 (+0800)
Subject: Fix error during DND from both Emacs and GTK at the same time
X-Git-Tag: emacs-29.0.90~1910^2~235
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=fe6f1dfeb4ad4aaf517d1ac34435f3750f7f4569;p=emacs.git

Fix error during DND from both Emacs and GTK at the same time

* src/xterm.c (x_dnd_get_target_window): Make mapping and
releasing the COW atomic.  This is to fix a rare bug when
MPX (multi-pointer X) is in use and the user tries to drag
from both GTK and Emacs at the same time using multiple seats.
---

diff --git a/src/xterm.c b/src/xterm.c
index edfb89070ff..34a40da548f 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -3524,10 +3524,13 @@ x_dnd_get_target_window (struct x_display_info *dpyinfo,
 				  dpyinfo->Xatom_NET_WM_CM_Sn) != None)
 	    {
 	      x_catch_errors (dpyinfo->display);
+	      XGrabServer (dpyinfo->display);
 	      overlay_window = XCompositeGetOverlayWindow (dpyinfo->display,
 							   dpyinfo->root_window);
 	      XCompositeReleaseOverlayWindow (dpyinfo->display,
 					      dpyinfo->root_window);
+	      XUngrabServer (dpyinfo->display);
+
 	      if (!x_had_errors_p (dpyinfo->display))
 		{
 		  XGetWindowAttributes (dpyinfo->display, overlay_window, &attrs);
@@ -3682,10 +3685,13 @@ x_dnd_get_target_window (struct x_display_info *dpyinfo,
 			      dpyinfo->Xatom_NET_WM_CM_Sn) != None)
 	{
 	  x_catch_errors (dpyinfo->display);
+	  XGrabServer (dpyinfo->display);
 	  overlay_window = XCompositeGetOverlayWindow (dpyinfo->display,
 						       dpyinfo->root_window);
 	  XCompositeReleaseOverlayWindow (dpyinfo->display,
 					  dpyinfo->root_window);
+	  XUngrabServer (dpyinfo->display);
+
 	  if (!x_had_errors_p (dpyinfo->display))
 	    {
 	      XGetWindowAttributes (dpyinfo->display, overlay_window, &attrs);