move the grid-specific workaround for scrollbar hysteresis to wxScrollHelper itself, the scrollbars now should not only appear but also disappear correctly during resizing

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@55627 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/grid.h

@@ -2036,6 +2036,10 @@ protected:
 
     friend class WXDLLIMPEXP_FWD_ADV wxGridSelection;
 
+private:
+    // implement wxScrolledWindow method to return m_gridWin size
+    virtual wxSize GetSizeAvailableForScrollTarget(const wxSize& size);
+
     DECLARE_DYNAMIC_CLASS( wxGrid )
     DECLARE_EVENT_TABLE()
     DECLARE_NO_COPY_CLASS(wxGrid)