keep correct default background but allow overriding it in user code too

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@34453 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/scrolbar.h

@@ -57,10 +57,11 @@ public:
     virtual bool MSWOnScroll(int orientation, WXWORD wParam,
                              WXWORD pos, WXHWND control);
 
-protected:
+    // override wxControl version to not use solid background here
+    virtual WXHBRUSH MSWControlColor(WXHDC pDC, WXHWND hWnd);
 
-    virtual WXHBRUSH DoMSWControlColor(WXHDC pDC, wxColour colBg, WXHWND hWnd);
-    wxSize DoGetBestSize() const;
+protected:
+    virtual wxSize DoGetBestSize() const;
     virtual WXDWORD MSWGetStyle(long style, WXDWORD *exstyle) const;
 
     int m_pageSize;