Correct handling of the combination of hyphenation and text-align = center, left or right.
At the end, I found out that this was not the same problem as bug 36533, but another bug specifically concerning the elements created to represent hyphens.
I think that Manuel has been the first person ever testing hyphenation together with non-justified text, thus awaking this sleeping bug! :-)
There is still a detail that has not yet been fixed: the correct handling of characters that can be used as break points (for example a "/" character in the middle of a long url, that could be used as an "emergency break"). I'm going to fix that too, I just wanted to commit this correction as soon as possible in order to avoid run time exceptions.