If you open it by visiting chrome://browser/content/places/places.xhtml in the address bar it defaults to "All Bookmarks".

Note that opening this chrome URI can cause issues and not all places feature may work properly as there have been such reports in the past and you shouldn't open the Library in more than one tab.

You can possibly achieve this via the autoconfig.cfg file in the Firefox installation folder.

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig

The folder that opens is set via this line in the autoconfig code, so in this case "Bookmarks Menu".

let showPlaces = ["AllBookmarks","BookmarksMenu","BookmarksToolbar","UnfiledBookmarks"][1];

• /questions/1373437 Mozilla Firefox - Manage Bookmarks - Default Folder

You can test in the Browser Console what folder opens, you can open (Ctrl+Shift+O) with any valid folder ID.

• https://firefox-source-docs.mozilla.org/devtools-user/browser_console/

selectPlaces = 0;
showPlaces = ["AllBookmarks","BookmarksMenu","BookmarksToolbar","UnfiledBookmarks"][selectPlaces];
PlacesCommandHook.showPlacesOrganizer(showPlaces);

Set "Browser:ShowAllBookmarks" to a specific folder:

 document.getElementById("Browser:ShowAllBookmarks").setAttribute("oncommand", "PlacesCommandHook.showPlacesOrganizer('BookmarksToolbar');");

If you open it by visiting chrome://browser/content/places/places.xhtml in the address bar it defaults to "All Bookmarks".

Thanks for responding, zeroknight. Alas, I have tried this solution in the past and it turned out to be quirky, as cor-el suggests.

You can possibly achieve this via the autoconfig.cfg file in the Firefox installation folder.

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig

The folder that opens is set via this line in the autoconfig code, so in this case "Bookmarks Menu". let showPlaces = ["AllBookmarks","BookmarksMenu","BookmarksToolbar","UnfiledBookmarks"][1];

• /questions/1373437 Mozilla Firefox - Manage Bookmarks - Default Folder

While everyone should be deeply grateful to the developers of FF, it's very corrupt to force people to constantly upgrade the app while removing features that your users value by ignoring their voices and not doing true regression testing on the user side. I was used to Ctl-Shift-B in older versions and re-learned Ctl-Shift-O and now that's been removed just to hide the Bookmarks Manager for end-users because we're supposedly "too dumb" to manage/organize our own Bookmarks. Instead, you prefer to copycat Chrome and send folks to do some wizardry to do a simple task and you wonder why the number of users are dwindling.

I have thousands of entries in my Bookmarks file (253 MB) that I can no longer organize even though the Bookmarks Manager sucked in the first place having been ignored for years by the developers. I suppose in the OSS spirit I'm supposed to poor into the code or, better yet, right a plug-in for this purpose since the core devs have much, much, much more important stuff to do (like speed, speed, speed at the price of stupid - reminds me of Google Search which AI will kill soon I hope) than to listen to the actual non-technical users of the software (or is it not made for this audience?) I suppose I could also be considered an edge case, so go make your own $h*& if you're not happy with ours.

Ending my rant, I guess I should move everything to Vivaldi now. After all, who cares about whether a piece of software is open source or not if you can get one just as pricey that fulfills your needs better. With the user base of such software being in the millions, who cares about loosing yet one more loyal user. As a Math graduate, I know numbers add/matter. Perhaps in the near future, we'll be able to ask an AI to build us a browser with exactly the features we'd like to have or ask it to stop our Firefox browser to upgrade automatically without our approval and remove the code that sneaks behind us to do that for us in the name of "security" and bull.

Well, I signed in just to give you good people my piece of mind (which will likely go to death ears but made me feel good for a moment). Keep chugging away, Agile fellas ... Adios!!!

"Ctrl+Shift+O" should still open the Bookmarks Manager (Library), this change was made to have the same access key on all platforms. See Bookmarks.

• https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perform-firefox-tasks-quickly

"Ctrl+B" is the keyboard shortcut to toggle the Bookmarks Sidebar. "Ctrl+Shift+B" is the keyboard shortcut to toggle the Bookmarks Toolbar. "Ctrl+Shift+O" is the keyboard shortcut to Open the Library.