No as far as I have understood it isn't a FF issue. It is you guys abusing a bug which has now been closed. Hopefully you aren't abusing it in the new forum too.
Except it works in every other browser, so FF is saying that they are correct and everyone else is wrong? and the WSISG editor is the same as the one used by all Vbul forums. You know not saying that Vbul is perfect, there are reasons we are moving to a new forum software.