Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp	(revision 91695)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.cpp	(revision 91696)
@@ -348,6 +348,13 @@
     else
     {
+        /* Should we send a hint? */
+        bool fSendHint = true;
         /* Do not send a hint if nothing has changed to prevent the guest being notified about its own changes: */
-        if ((int)frameBuffer()->width() != size.width() || (int)frameBuffer()->height() != size.height())
+        if (fSendHint && (int)frameBuffer()->width() == size.width() && (int)frameBuffer()->height() == size.height())
+            fSendHint = false;
+        /* Do not send a hint if GA supports graphics and we have sent that hint already: */
+        if (fSendHint && uisession()->isGuestSupportsGraphics() && m_lastSizeHint == size)
+            fSendHint = false;
+        if (fSendHint)
         {
             LogRel(("GUI: UIMachineView::sltPerformGuestResize: Sending guest size-hint to screen %d as %dx%d\n",
@@ -362,4 +369,5 @@
                                        0 /* bits per pixel */,
                                        true /* notify? */);
+            m_lastSizeHint = size;
         }
     }
Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.h
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.h	(revision 91695)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIMachineView.h	(revision 91696)
@@ -373,4 +373,9 @@
     QSize m_sizeHintOverride;
 
+    /** Last size hint sent as a part of guest auto-resize feature.
+      * @note Useful to avoid spamming CDisplay with same hint before
+      *       frame-buffer finally resized to requested size. */
+    QSize  m_lastSizeHint;
+
     /** Holds current host-screen number. */
     int m_iHostScreenNumber;