mnAllSaveBackSize only set not read

Change-Id: Ibc5a2313b0231613b3c41002c144672140bf31dd

vcl/inc/window.h

@@ -127,7 +127,6 @@ struct ImplFrameData
     sal_Int32           mnDPIX;                 //< Original Screen Resolution
     sal_Int32           mnDPIY;                 //< Original Screen Resolution
     ImplMapRes          maMapUnitRes;           //< for LogicUnitToPixel
-    sal_uIntPtr         mnAllSaveBackSize;      //< size of all bitmaps of saved backgrounds
     ImplSVEvent *       mnFocusId;              //< FocusId for PostUserLink
     ImplSVEvent *       mnMouseMoveId;          //< MoveId for PostUserLink
     long                mnLastMouseX;           //< last x mouse position

vcl/source/window/clipping.cxx

@@ -850,7 +850,6 @@ void Window::ImplDeleteOverlapBackground()
 {
     if ( mpWindowImpl->mpOverlapData->mpSaveBackDev )
     {
-        mpWindowImpl->mpFrameData->mnAllSaveBackSize -= mpWindowImpl->mpOverlapData->mnSaveBackSize;
         mpWindowImpl->mpOverlapData->mpSaveBackDev.disposeAndClear();
         if ( mpWindowImpl->mpOverlapData->mpSaveBackRgn )
         {

vcl/source/window/window.cxx

@@ -1033,7 +1033,6 @@ void Window::ImplInit( vcl::Window* pParent, WinBits nStyle, SystemParentData* p
         mpWindowImpl->mpFrameData->mpFirstBackWin     = nullptr;
         mpWindowImpl->mpFrameData->mpFontCollection   = pSVData->maGDIData.mpScreenFontList;
         mpWindowImpl->mpFrameData->mpFontCache        = pSVData->maGDIData.mpScreenFontCache;
-        mpWindowImpl->mpFrameData->mnAllSaveBackSize  = 0;
         mpWindowImpl->mpFrameData->mnFocusId          = nullptr;
         mpWindowImpl->mpFrameData->mnMouseMoveId      = nullptr;
         mpWindowImpl->mpFrameData->mnLastMouseX       = -1;