These functions are: DCanvas::DrawTextCommon, V_BreakLines and FFont::StringWidth.
This will allow strings from UTF-8 encoded assets to display properly, but also handle the OpenAL device name on international systems, as this will be returned as an UTF-8 string.
Due to backwards compatibility needs the decoding function is rather lax to allow both UTF-8 and ISO 8859-1 to pass through correctly - and this also implies that it will allow mixed encodings which may happen if strings from different sources get concatenated.
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