This ctor was not documented at all because the comment preceding it was a
plain C++ comment and not a Doxygen one.
Do it now, especially as the logic of this ctor is not quite obvious.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69976 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Use "wxWindows licence" and not "wxWidgets licence" (the latter doesn't
exist) and consistently spell "licence" using British spelling.
See #12165.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64940 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
