Index: /trunk/src/VBox/Additions/x11/VBoxClient/seamless-x11.cpp
===================================================================
--- /trunk/src/VBox/Additions/x11/VBoxClient/seamless-x11.cpp	(revision 50374)
+++ /trunk/src/VBox/Additions/x11/VBoxClient/seamless-x11.cpp	(revision 50375)
@@ -536,6 +536,6 @@
     XClientMessageEvent clientMessage = { ClientMessage, 0, 0, 0, 0, 0, 8 };
 
-    if (0 != XSendEvent(mDisplay, DefaultRootWindow(mDisplay), false, PropertyChangeMask,
-                   reinterpret_cast<XEvent *>(&clientMessage)))
+    if (XSendEvent(mDisplay, DefaultRootWindow(mDisplay), false,
+                   SubstructureNotifyMask, (XEvent *)&clientMessage))
     {
         XFlush(mDisplay);