diff --git a/vcl/source/window/toolbox.cxx b/vcl/source/window/toolbox.cxx
index bd64166..8ff4c02 100644
--- a/vcl/source/window/toolbox.cxx
+++ b/vcl/source/window/toolbox.cxx
@@ -2492,7 +2492,18 @@ void ToolBox::ImplFormat( bool bResize )
                             // items here. ( Note: assume mnMaxItemHeight is
                             // equal to the LineSize when multibar has a single
                             // line size )
-                            it->maCalcRect.Top()      =  it->maRect.Top() ? it->maRect.Top() : ( nY + ( mnMaxItemHeight-aCurrentItemSize.Height())/2 );
+                            // 1. But on Windows7(with Aero), it->maRect.Top()
+                            // is always 0, probably.Unfortunately mnMaxItemHeight
+                            // isn't updated immediately when the calc bar is
+                            // expanded. We need to consider these. Please refer
+                            // tdf83099.
+                            if ( it->maRect.Top() ) {
+                                it->maCalcRect.Top() = it->maRect.Top();
+                            } else if ( mnMaxItemHeight >= aCurrentItemSize.Height() ) {
+                                it->maCalcRect.Top() = nY + ( mnMaxItemHeight-aCurrentItemSize.Height())/2;
+                            } else {
+                                it->maRect.Top() = 0; // workaround for Windows7 with Aero
+                            }
                         }
                         else
                             it->maCalcRect.Top()      = nY+(nLineSize-aCurrentItemSize.Height())/2;
@@ -2516,6 +2527,9 @@ void ToolBox::ImplFormat( bool bResize )
                     if ( it->mbShowWindow )
                     {
                         Point aPos( it->maCalcRect.Left(), it->maCalcRect.Top() );
+
+                        assert( it->maCalcRect.Top() >= 0 );
+
                         it->mpWindow->SetPosPixel( aPos );
                         if ( !mbCustomizeMode )
                             it->mpWindow->Show();