First of all I want to point that browsers can open PDF but not in IWP.
Instead to point to PDF from web viewer, embed link to PDF in container field.
You cannot view PDF but are able to download it.
I don't think that you can get result with FF or Chrome - open PDF. But with mentioned you can download it via FF or Chrome
Turns out it is a problem wiht the Active X script and the way firefox doesn't render it.
found a plug in that works just fine.
I don't get why you don't post your solution. I have the same problem and it would be nice to know which plugin this is...
the plug in is for firefox. it's called Coral IE tab. basically switched the rendering engine to IE within the FF browser. you can have it filter so when you go to the FM IWP database it automatically switches.