Hi jcl-ff,
Sorry you have problems with this. Firefox should work!

Maybe a Mac user will be along and test this to confirm it works. Can you give another couple of sites where you see this problem. It works ok for me on Linux. I see a scrollbar when javascript is enabled (not blocked).

1. Please try in a new additional temporary clean profile, from safe mode and with all plugins disabled. Does that work ?

• see Profile Manager - Create, remove or switch Firefox profiles_creating-a-profile
  you will already be ware of Diagnose Firefox issues using Troubleshoot Mode

You should also clear the Firefox cache and the site cookies, and close all but a blank new tab tabs between testing each site.

• Clear cookies and site data in Firefox_delete-cookies-for-a-single-site
• How to clear the Firefox cache
• and maybe also Firefox can't load websites but other browsers can

New profile and safe mode don't matter. Delete cookies & cache don't matter.

Another example site is www.facebook.com where the Day field under birthdate only goes to 19. It happens on most (all?) sites with a long drop down list.

This is probably OS X & Firefox version related. Same problem on another mac running 10.7, but not on an old one running 10.4. It used to work with older versions of Firefox, but I don't recall what version #.

attached screenshot from bank website.

This will be a silly question. Was there a sliding bar on the right side of the choices? Did you try moving the bar up & down?

At least you have a workaround in that the arrow key works.

Quick check
Before looking for deeper problems let's not overlook the obvious common solution cookies or cache.

• Reload using (Mac equivalent of Cmd+f5) Ctrl+ Shift+R.
  If that does not help Close all tabs except a final one relating to the problem site and:
  1. Clear the Firefox cache How to clear the Firefox cache
  2. and the site cookies
     Clear cookies and site data in Firefox_delete-cookies-for-a-single-site
  3. then try again with the problem site.

As you see the problem on multiple sites I doubt the above will help, but you would regret it if if it does and you failed to try it. It could also help other readers of this thread.

Anyone else seeing this ?
This is likely to need help from other Mac users to discover what it affects. There have been reported problems with scrolling but that usually seems to relate to touch-screens &/or scrolling of Windows not the dropdown lists.

• as in this mailing list discussion http://productforums.google.com/forum/?_escaped_fragment_=topic/chrome/FjjdquTVNBE#!topic/chrome/FjjdquTVNBE
• See for instance this recent answer by Alice although again problems seem mainly to be gestures etc. problems /questions/979427#answer-508330 & this older thread posted on Apple's forum, in case it helps:
  https://discussions.apple.com/message/23541760#23541760 Mavericks and Firefox scrolling

It seems possible that the problem will be with your particular install, because, otherwise there would be noticeable reporting of problems. Half of Mac users of Bank Of America for instance would likely have internet banking services fail.

You have already discovered it may be Firefox & OS X version dependent, although of course it could be other factors that differ in the other machines. Try to compare the setups for any other differences and clues.

Please Try
Whilst waiting to see if others chime in may I suggest a couple of things you could try that may help narrow this down.

1. Testing using an additional new clean profile with all plugins disabled
   Profile Manager - Create, remove or switch Firefox profiles_5-reinstall-firefox. (I did note you have tried safemode already)
2. Installing and running Firefox 24 ESR as an additional browser as a test.
   http://www.mozilla.org/en-US/firefox/organizations/
   http://kb.mozillazine.org/Testing_pre-release_versions#Installing_multiple_versions
   (ESR is not intended for use by private individuals, but is secure. It is an older fully developed and tested Firefox version)

edit modified instruction on cache & cookies

The Facebook "day" drop-down menu under birthdate should have a scrollbar (I'll attach a Windows screenshot)

Maybe this article will help?
http://heresthethingblog.com/2013/02/25/mac-tip-missing-scroll-bars/

Thanks AliceWyman

You're welcome. Thanks for posting back.

For the record, this is the solution, copied from http://heresthethingblog.com/2013/02/25/mac-tip-missing-scroll-bars/

   Click the Apple menu at the top-left of the screen, then select System Preferences.
   Next, select the General preferences pane; it’s the very first one, up at the top.
   Under the “Show scroll bars” heading, you’ll find three options: “Automatically based on input device,” “When scrolling,” and “Always.”
   Go ahead and select that last “Always” option. You’re done!