Time format in chapter file hh:mm:ss.xxx

How can we use a time format hh:mm:ss.xxx in the chapter file movie.chf. :?:
With the actual hh:mm:ss without fraction of second, we loose the exact time of chapter like in DVD abd chapter often start by a half second flash of previous chapter image :(
It's only aesthetic but will improve this great movie player :D :D
Chapter file line should be like "3=00:18:55.880 Chapter title"

Thierry