In menuutils.cpp, line 940 and 941 there is the same string. The extracting tool using xgettext see these two lines as only one, with twice the same string proposed for translation and separated by a \n. In this case, in a wxASSERT, I suppose that only the english string is needed, not the translated one. May be a better code could be :
wxASSERT_MSG(data == NULL,
wxT("wxMenuShortcutWalker does not use the 'data' parameter") // English only.
);
and keep wxT (or _T) to be wx 2.8 compatible.
gd_on