With current HEAD, when compiling the line

	switch ( field.Last() ) {

beign "field" a wxString, I get

Format.cpp: In member function ‘CFormat& CFormat::operator%(double)’:
Format.cpp:215: error: ambiguous default type conversion from ‘wxUniCharRef’
Format.cpp:215: error:   candidate conversions include ‘wxUniCharRef::operator char() const’ and ‘wxUniCharRef::operator int() const’

This did not happen with 2.8, and forces a explicit cast, so apps using it break.