Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/fullscreen/UIMachineWindowFullscreen.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/fullscreen/UIMachineWindowFullscreen.cpp	(revision 59813)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/fullscreen/UIMachineWindowFullscreen.cpp	(revision 59814)
@@ -232,5 +232,5 @@
         UICocoaApplication::instance()->registerToNotificationOfWindow("NSWindowDidFailToEnterFullScreenNotification", this,
                                                                        UIMachineWindow::handleNativeNotification);
-    }
+}
 #endif /* Q_WS_MAC */
 }
@@ -483,2 +483,18 @@
 #endif /* Q_WS_WIN || Q_WS_X11 */
 
+#ifdef Q_WS_WIN
+# if QT_VERSION >= 0x050000
+void UIMachineWindowFullscreen::showEvent(QShowEvent *pEvent)
+{
+    /* Expose workaround again,
+     * Qt devs will never fix that it seems.
+     * This time they forget to set 'Mapped'
+     * attribute for initially frame-less window. */
+    setAttribute(Qt::WA_Mapped);
+
+    /* Call to base-class: */
+    UIMachineWindow::showEvent(pEvent);
+}
+# endif /* QT_VERSION >= 0x050000 */
+#endif /* Q_WS_WIN */
+
Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/fullscreen/UIMachineWindowFullscreen.h
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/fullscreen/UIMachineWindowFullscreen.h	(revision 59813)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/fullscreen/UIMachineWindowFullscreen.h	(revision 59814)
@@ -102,4 +102,11 @@
 #endif /* Q_WS_WIN || Q_WS_X11 */
 
+#ifdef Q_WS_WIN
+# if QT_VERSION >= 0x050000
+    /** Win: Handles show @a pEvent. */
+    void showEvent(QShowEvent *pEvent);
+# endif /* QT_VERSION >= 0x050000 */
+#endif /* Q_WS_WIN */
+
 #if defined(Q_WS_WIN) || defined(Q_WS_X11)
     /** Holds the mini-toolbar instance. */
Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.cpp	(revision 59813)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.cpp	(revision 59814)
@@ -267,18 +267,19 @@
 #endif /* Q_WS_WIN || Q_WS_X11 */
 
-#if defined(VBOX_WITH_TRANSLUCENT_SEAMLESS) && defined(Q_WS_WIN)
-void UIMachineWindowSeamless::showEvent(QShowEvent *pShowEvent)
-{
-    /* Call to base class: */
-    UIMachineWindow::showEvent(pShowEvent);
-
-    /* Following workaround allows to fix the next Qt BUG:
-     * https://bugreports.qt-project.org/browse/QTBUG-17548
-     * https://bugreports.qt-project.org/browse/QTBUG-30974
-     * Widgets with Qt::WA_TranslucentBackground attribute
-     * stops repainting after minimizing/restoring, we have to call for single update. */
-    QApplication::postEvent(this, new QEvent(QEvent::UpdateRequest), Qt::LowEventPriority);
-}
-#endif /* VBOX_WITH_TRANSLUCENT_SEAMLESS && Q_WS_WIN */
+#ifdef Q_WS_WIN
+# if QT_VERSION >= 0x050000
+void UIMachineWindowSeamless::showEvent(QShowEvent *pEvent)
+{
+    /* Expose workaround again,
+     * Qt devs will never fix that it seems.
+     * This time they forget to set 'Mapped'
+     * attribute for initially frame-less window. */
+    setAttribute(Qt::WA_Mapped);
+
+    /* Call to base-class: */
+    UIMachineWindow::showEvent(pEvent);
+}
+# endif /* QT_VERSION >= 0x050000 */
+#endif /* Q_WS_WIN */
 
 #ifdef VBOX_WITH_MASKED_SEAMLESS
Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.h
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.h	(revision 59813)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.h	(revision 59814)
@@ -74,8 +74,10 @@
 #endif /* Q_WS_WIN || Q_WS_X11 */
 
-#if defined(VBOX_WITH_TRANSLUCENT_SEAMLESS) && defined(Q_WS_WIN)
-    /** Windows: Translucency stuff workaround. */
+#ifdef Q_WS_WIN
+# if QT_VERSION >= 0x050000
+    /** Win: Handles show @a pEvent. */
     void showEvent(QShowEvent *pEvent);
-#endif /* VBOX_WITH_TRANSLUCENT_SEAMLESS && Q_WS_WIN */
+# endif /* QT_VERSION >= 0x050000 */
+#endif /* Q_WS_WIN */
 
 #ifdef VBOX_WITH_MASKED_SEAMLESS