Firstly, I'm really glad to have found this topic - and therefore know I'm not the only one suffering this issue.
I had thought it was something dodgy in my coding - but couldn't figure why IE was ok - but FF not.
I use FusionCharts for internal corp dashboards. As IE is the only 'officially' supported browser by IT - I can use that excuse for a while. However, there are > 20 key customers (and me) who are FF users, so this is not really workable.
I eagerly await a fix - either from the FC team or the outcome of the Bugzilla report....