From 3ce9a4a179a5f74d3bda191b7c7b7905225715a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Fl=C3=B6ser?= <mgraesslin@kde.org>
Date: Sat, 30 Sep 2017 16:29:42 +0200
Subject: [PATCH] [tabbox] Guard Xcb::sync with whether we have an X11
 connection

Otherwise crash on WaylandOnly once you Alt+Tab. Credits go to our
integration tests for finding this issue!
---
 tabbox/tabbox.cpp        | 4 +++-
 tabbox/tabboxhandler.cpp | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/tabbox/tabbox.cpp b/tabbox/tabbox.cpp
index c5d53dce92..f397d791f4 100644
--- a/tabbox/tabbox.cpp
+++ b/tabbox/tabbox.cpp
@@ -777,7 +777,9 @@ void TabBox::hide(bool abort)
     if (isDisplayed())
         qCDebug(KWIN_TABBOX) << "Tab box was not properly closed by an effect";
     m_tabBox->hide(abort);
-    Xcb::sync();
+    if (kwinApp()->x11Connection()) {
+        Xcb::sync();
+    }
 }
 
 void TabBox::reconfigure()
diff --git a/tabbox/tabboxhandler.cpp b/tabbox/tabboxhandler.cpp
index 9edfca2e54..9d8f16ce78 100644
--- a/tabbox/tabboxhandler.cpp
+++ b/tabbox/tabboxhandler.cpp
@@ -384,7 +384,9 @@ void TabBoxHandler::show()
         d->show();
     }
     if (d->config.isHighlightWindows()) {
-        Xcb::sync();
+        if (kwinApp()->x11Connection()) {
+            Xcb::sync();
+        }
         // TODO this should be
         // QMetaObject::invokeMethod(this, "initHighlightWindows", Qt::QueuedConnection);
         // but we somehow need to cross > 1 event cycle (likely because of queued invocation in the effects)