Problems with Firefox4 and Safari5

[Duffelding]

Hello,

Around 2 years ago we developed a Flash based website for a client.
Back then we used SWFFit to resize the containing div to let the user
scroll the page (with its changing heights) via the browsers
scrollbar. Until a few months ago, it worked fine.

Unfortunately, new Browser versions introduced some issues:

+ Safari 5 shows screen flickering, when the object is resized
+ Firefox 4 animates the resizing with a weird scaling transition,
even worse sometimes gets stuck with weird artefacts until the mouse
is moved over the object

I dove into the script and found that the core of the problem is not
SWFFit, but the browsers itself. Changing the height of the flash
object triggers these problems, even with a very extracted version of
the application without SWFFit.

Altough setting wmode to transparent or oqaque is fixing the problems,
it is not an option since the application is running way too slow.

I tried every possible combination with different container divs and
dimensions, no luck so far. Is there a trick to avoid these bugs?

Thanks

Franz