In reply to MM0FMF and DJ0GM:
OK, this one had me hooked!
I installed Seamonkey 2.0.4 on my Ubuntu Linux system.
Tried the database, and indeed the drop down menus don’t appear.
Installed User Agent Switcher
(do it from within Seamonkey as it likes to do the install itself).
This adds options to the “Tools” menu in the browser, which enables you to select, for example, IE7 as the User Agent, rather than the “default user agent”. I did find the menu arrangement a bit peculiar, but it works.
There’s a “test user agent switcher” option so you can check it has done what you think.
The drop down menus then work fine in Seamonkey.
Note it still displays stuff as Seamonkey would, but it pretends to the server that you are using IE7 or whatever, so the scripting is allowed. Wild!
I still prefer Firefox …