added wxDC::CopyAttributes() and use it in wxBufferedDC to ensure that wxAutoBufferedPaintDC font is correctly initialized from the window font, as it already happens with wxPaintDC that it mimics

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60846 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dc.h

@@ -702,6 +702,9 @@ private:
 class WXDLLIMPEXP_CORE wxDC : public wxObject
 {
 public:
+    // copy attributes (font, colours and writing direction) from another DC
+    void CopyAttributes(const wxDC& dc);
+
     virtual ~wxDC() { delete m_pimpl; }
 
     wxDCImpl *GetImpl()