If @a str is used, data written to the stream is appended to the current
contents of it, i.e. the string is not cleared here. However if it is not
empty, the positions returned by wxOutputStream::TellO will be
offset by the initial string length, i.e. initial stream position will be the
initial length of the string and not 0.
If @a str is used, data written to the stream is appended to the current
contents of it, i.e. the string is not cleared here. However if it is not
empty, the positions returned by wxOutputStream::TellO will be
offset by the initial string length, i.e. initial stream position will be the
initial length of the string and not 0.