Bookmark folder drop down menu disappears

Question

While using Firefox as of late, I've noticed a few things out of place.
Firstly, while browsing the web I tend to store a lot of bookmarks; recently while attempting to store new bookmarks in folders on the bookmark toolbar, as I drag the page to be stored as a bookmark the folder's drop down menu disappears. It's still possible to drop the bookmark into the folder, which then in turn makes it fall to the bottom of the list automatically; however, there are organized folders inside of folders so it's rather counterproductive.
The same thing happens when just clicking on a folder, the menu simply doesn't show up yet the "invisible" bookmarks may be interacted with by clicking on them -albeit randomly. After a few attempts, the menu will eventually appear but not always the first attempt. Quite frustrating.
Also, the memory used by Firefox seems a bit high; especially when opening various new tabs.
What should be done about this issue?

Answer 1

(1) Find (or create) the chrome folder. This is a folder in your currently active Firefox settings folder, also known as your Firefox profile folder.
Open the your profile folder using: Help > Troubleshooting Information
Windows: Click the Show Folder button
Mac: Click the Show in Finder button
Check for a chrome folder.
If it exists, double-click it to open it.
If it does not exist, create a chrome folder, then double-click it to open it.
(2) Create or Edit a userChrome.css file by adding a bookmark button rule.
Check for a userChrome.css file in the chrome folder.
If it exists, open it in a text editor and add the following lines, then save:
/* Force bookmark drop-down button display even with classic menu bar */
#bookmarks-menu-button {display:-moz-box !important}
If it does not exist, right-click the following link > Save Link As, and save into your chrome folder (or save in Downloads and drag to your chrome folder): http://www.jeffersonscher.com/res/userChrome-bookmarksbutton.css.
Then rename the file to userChrome.css.