Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UISession.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UISession.cpp	(revision 50800)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UISession.cpp	(revision 50801)
@@ -821,9 +821,7 @@
     if (changeType == KGuestMonitorChangedEventType_NewOrigin)
         return;
-    /* Ignore KGuestMonitorChangedEventType_Disabled event if there is only one window visible: */
+    /* Ignore KGuestMonitorChangedEventType_Disabled event for primary screen: */
     AssertMsg(countOfVisibleWindows() > 0, ("All machine windows are hidden!"));
-    if (   changeType == KGuestMonitorChangedEventType_Disabled
-        && countOfVisibleWindows() == 1
-        && isScreenVisible(uScreenId))
+    if (changeType == KGuestMonitorChangedEventType_Disabled && uScreenId == 0)
         return;