Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp	(revision 29557)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp	(revision 29558)
@@ -615,4 +615,11 @@
         display.SetFramebuffer(m_uScreenId, CFramebuffer(m_pFrameBuffer));
     }
+
+#ifdef Q_WS_X11
+    /* Processing pseudo resize-event to synchronize frame-buffer with stored framebuffer size: */
+    QSize size = guestSizeHint();
+    UIResizeEvent event(FramebufferPixelFormat_Opaque, NULL, 0, 0, size.width(), size.height());
+    frameBuffer()->resizeEvent(&event);
+#endif /* Q_WS_X11 */
 }
 
Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/normal/UIMachineWindowNormal.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/normal/UIMachineWindowNormal.cpp	(revision 29557)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/normal/UIMachineWindowNormal.cpp	(revision 29558)
@@ -561,14 +561,13 @@
 
         /* Normalize view to the optimal size:
-           Note: Cause of the async behavior of some Linux WM's we have to
-           delay this a little bit. On Mac OS X this is not necessary and
-           create even wrong resize events. So there we set the geometry
-           immediately. */
+         * Note: Cause of the async behavior of X11 (at least GNOME) we have to delay this a little bit.
+         * On Mac OS X and MS Windows this is not necessary and create even wrong resize events.
+         * So there we set the geometry immediately. */
         if (machineView())
-#if defined(Q_WS_MAC) || defined(Q_WS_WIN)
+#ifdef Q_WS_X11
+            QTimer::singleShot(0, machineView(), SLOT(sltNormalizeGeometry()));
+#else /* Q_WS_X11 */
             machineView()->normalizeGeometry(true);
-#else /* Q_WS_MAC || Q_WS_WIN */
-            QTimer::singleShot(0, machineView(), SLOT(sltNormalizeGeometry()));
-#endif /* Q_WS_MAC || Q_WS_WIN */
+#endif /* !Q_WS_X11 */
     }