check if current iterator position is smaller than end, not equal

there's possibility that position at start will be greater
than ending iterator, so the iteration must not be started

src/helpers.cpp

@@ -845,7 +845,7 @@ void Scroller(Window &w, const string &string, size_t width, size_t &pos)
 #		endif
 		len = 0;
 		std::basic_string<my_char_t>::const_iterator b = s.begin(), e = s.end();
-		for (std::basic_string<my_char_t>::const_iterator it = b+pos; it != e && len < width; it++)
+		for (std::basic_string<my_char_t>::const_iterator it = b+pos; it < e && len < width; it++)
 		{
 #			ifdef _UTF8
 			len += wcwidth(*it);