Add wxCONTROL_NONE which is just a symbolic name for 0 and use it in the code to avoid g++ 4.8 warnings about mixing enum and int in conditional expression. Closes #16242. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76484 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775