New Release - Firmware Version 1.04.31_V for WD TV Live (4/6/11)

A bluray rip with PGS subtitles does not place a border around the text. I convert to idx/sub and then place this outside the MKV container to produce the black outline. Why is the same idx/sub file displayed incorrectly (without a black border) when placed in the MKV container - is it something to do with MKV and not the WDTV? Obviously it’s not a big issue since it can be solved by me, more of a curiosity.