Firefox appears not to handle the height of the areas if this height is set in percentages, e.g. "height=80%". But Firefox handles it if the value is given in pixels, like so: "height=500px".
The Workbench Organizer in Bibledit-Web now has the option to set the height in % or in px.
Hopefully it enables the use of Firefox in this scenario now.
Teus.