What will be happening is m_lastUtf8Text will be set to the hint and m_lastText will be set to empty (and/or the flashing cursor depending on focus state).  Thus, SetText() here won't do anything as the last utf8 text was what we're trying to fix.

i.e. the correct fix for this would be in fixing CGUITextLayout so that SetTextW() called after SetText() correctly resets the utf8 field.