From d3f3bf105b64a47a995c5e4c1bd4f18761250702 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ralf=20Cors=C3=A9pius?= <corsepiu@fedoraproject.org>
Date: Wed, 17 Feb 2016 15:16:29 +0100
Subject: [PATCH 5/9] dx-null

---
 src/exec/libdx/xwindow.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/exec/libdx/xwindow.c b/src/exec/libdx/xwindow.c
index ab25786..48e195c 100644
--- a/src/exec/libdx/xwindow.c
+++ b/src/exec/libdx/xwindow.c
@@ -29,7 +29,9 @@ Error
 DXRegisterWindowHandlerWithCheckProc(Error (*proc) (int, Pointer),
 		int (*check)(int, Pointer), Display *d, Pointer arg)
 {
-    int fd = ConnectionNumber(d);
+    int fd;
+    if (d) fd = ConnectionNumber(d);
+    else return ERROR;
 
     if (! DXRegisterInputHandlerWithCheckProc(proc, check, fd, arg))
 	return ERROR;
-- 
2.9.3