don't use deprecated wxImage methods inside wxWin

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@14751 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dataobj.cpp

@@ -358,7 +358,7 @@ void wxBitmapDataObject::DoConvertToPng()
     wxCHECK_RET( wxImage::FindHandler(wxBITMAP_TYPE_PNG) != NULL,
                  wxT("You must call wxImage::AddHandler(new wxPNGHandler); to be able to use clipboard with bitmaps!") );
 
-    wxImage image(m_bitmap);
+    wxImage image = m_bitmap.ConvertToImage();
 
     wxCountingOutputStream count;
     image.SaveFile(count, wxBITMAP_TYPE_PNG);