FancyMainWindow: Don't relay enter events as leave events

Change-Id: Ia92929d69d8d25b926be3061dbe3ee5dc95ff44a
(cherry picked from commit f6fea87a4d)
Reviewed-by: Ulf Hermann <ulf.hermann@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/libs/utils/fancymainwindow.cpp

@@ -248,7 +248,7 @@ public:
     void enterEvent(QEvent *event)
     {
         QApplication::instance()->installEventFilter(this);
-        QDockWidget::leaveEvent(event);
+        QDockWidget::enterEvent(event);
     }
 
     void leaveEvent(QEvent *event)