Try this addon - Add Bookmark Here ² :
https://addons.mozilla.org/en-US/firefox/addon/3880

Still does not present pop down of complete Bookmark folder list from which to choose where to save bookmark.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

See also http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

Open the Bookmarks Menu folder to see the folders in that folder.

This did the trick. In first safe mode pop up I checked 'Disable Add-ons' and closed, then restarted in normal. Now they all show up when right (to the right) arrow is selected.

Many thanks.

error

It's back. I've done everything here. I've saved bookmarks, uninstalled, then reinstalled program. It installs with bookmarks from save. On opening to home page, then selecting 'Bookmark this page', then selecting 'Show all the bookmarks folders' arrow it works once. On next (2nd) website and thereafter, that arrow only shows the three categories (toolbar, menu, unsorted). Have no add-ons. Need help.

You can check for a corrupted places.sqlite.

See http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

cor-el, I did everything as instructed regarding every places.sqlite entry; there were none showing as corrupt; I deleted all there were as the article instructed, it made no difference. This is a new computer and my previous OS was 98 and Firefox version was 2.0 something. I was able successfully import them. I never had any trouble w/ previous version of any type for years. As I said, it performs correctly the first time after starting Firefox 3.6, but not there after. If I uninstall again, do I check mark the prompt asking to uninstall personal settings (or something along those lines)?

the-edmeis, I can see them there, that is not at issue. They do not display repeatedly during 'Bookmark This Page' operation when selecting 'Show all bookmarks' arrow. Thanks.

To all, embarrassingly enough, I have discovered that I didn't know how to expand the three categories including 'Bookmarks Menu' in the 'Bookmark This Page' pop up interface. It was expanded by default on the initial Firefox opening and first page bookmark attempt. Next use it only showed categories. I clicked and double clicked the 'Bookmarks Menu' line, but failed to see the small, shaded triangle used to expand/collapse list. If it appears collapsed, just tap triangle at left of line to see all folders. It seems to open the same way after I do it for first time. Sorry for the inconvenience, and thanks for all the attempts to help.

Glad you figured it out, but we have the problem as you initially described. We knew to expand the list and we have only 5 of our 50+ bookmark folders showing in the Add Bookmark drop-down (I hate that thing). We'll try the Safe Mode and see if it's one of the handful of add-ins we use.

This worked for me (Ubuntu 10.10):
1. Backup bookmarks using the >Bookmarks>OrganizeBookmarks>ImportAndBackup>Backup (save file to desktop or some other non-mozilla directory).
2. Start firefox in Safe Mode ("firefox -safe-mode") ...a dialog pops up offering several options: select "Delete all bookmarks except for backups".
3. Restore bookmarks using the >Bookmarks>OrganizeBookmarks>ImportAndBackup>Restore> (and navigate to file backed-up in step 1).

  ...that's all and my subdirectories now show!