wxRTC functions now operate on the currently focused object, which by default is the whole buffer.
Up to three property commands are now shown on the context menu, depending on
available objects in the current hierarchy.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66680 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775