In wxMSW, use IRichEditOleCallback::GetContextMenu() to provide our
default context menu for rich text controls, instead of using
EVT_CONTEXT_MENU.
The latter completely overrides native control's handling and in
particular breaks Windows 8's builtin spellchecking support.
Fall back to the previous non-OLE code for older richtext versions.
Also make the new MSWCreateContextMenu() method virtual so that the
context menu can be customized.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76723 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
bd650ec3d9