ImplOverlapData is no longer used

Change-Id: I8fac0daefbafc9fe9e4d6cd385f543e14ac15f8a

vcl/inc/window.h

@@ -102,11 +102,6 @@ struct ImplWinData
                         maTopWindowChildren;
 };
 
-struct ImplOverlapData
-{
-    vcl::Region*        mpSaveBackRgn;          //< saved region, which must be invalidated
-};
-
 struct ImplFrameData
 {
     Idle                maPaintIdle;            //< paint idle handler
@@ -188,7 +183,6 @@ public:
     ~WindowImpl();
 
     ImplWinData*        mpWinData;
-    ImplOverlapData*    mpOverlapData;
     ImplFrameData*      mpFrameData;
     SalFrame*           mpFrame;
     SalObject*          mpSysObj;

vcl/source/window/window.cxx

@@ -550,9 +550,6 @@ void Window::dispose()
         delete mpWindowImpl->mpWinData;
     }
 
-    // cleanup overlap related window data
-    delete mpWindowImpl->mpOverlapData;
-
     // remove BorderWindow or Frame window data
     mpWindowImpl->mpBorderWindow.disposeAndClear();
     if ( mpWindowImpl->mbFrame )
@@ -612,7 +609,6 @@ WindowImpl::WindowImpl( WindowType nType )
     maWinRegion                         = vcl::Region(true);
     maWinClipRegion                     = vcl::Region(true);
     mpWinData                           = nullptr;                      // Extra Window Data, that we don't need for all windows
-    mpOverlapData                       = nullptr;                      // Overlap Data
     mpFrameData                         = nullptr;                      // Frame Data
     mpFrame                             = nullptr;                      // Pointer to frame window
     mpSysObj                            = nullptr;
@@ -930,13 +926,6 @@ void Window::ImplInit( vcl::Window* pParent, WinBits nStyle, SystemParentData* p
     ImplInsertWindow( pParent );
     mpWindowImpl->mnStyle = nStyle;
 
-    // Overlap-Window-Data
-    if ( mpWindowImpl->mbOverlapWin )
-    {
-        mpWindowImpl->mpOverlapData                   = new ImplOverlapData;
-        mpWindowImpl->mpOverlapData->mpSaveBackRgn    = nullptr;
-    }
-
     if( pParent && ! mpWindowImpl->mbFrame )
         mbEnableRTL = AllSettings::GetLayoutRTL();