using common implementation avoiding out-of-order redraws

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77031 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
fixing background style 

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77032 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775