I believe add-ons are limited to http: and https: addresses.

There is a trick involving a special kind of startup file called an Autoconfig file. (There actually are two files involved in making it work.)

You can see the rough outlines of the approach in this thread:

https://support.mozilla.org/en-US/questions/1251199#answer-1199709

That code might need to be updated for Firefox 76:

https://support.mozilla.org/questions/1283835

(snip)

I believe add-ons are limited to http: and https: addresses. There is a trick involving a special kind of startup file called an Autoconfig file. (There actually are two files involved in making it work.) You can see the rough outlines of the approach in this thread: https://support.mozilla.org/en-US/questions/1251199#answer-1199709 That code might need to be updated for Firefox 76: https://support.mozilla.org/questions/1283835

Thanks for the reply jscher2000. I want to give this a try, but I am using Firefox Portable and I'm not sure where those two autoconfig files go.

So far, I've tried

FirefoxPortable > Data > profile

FirefoxPortable > Data > profile > chrome

FirefoxPortable > App > firefox64

FirefoxPortable > App > firefox64 > browser.

I believe add-ons are limited to http: and https: addresses. There is a trick involving a special kind of startup file called an Autoconfig file. (There actually are two files involved in making it work.) You can see the rough outlines of the approach in this thread: https://support.mozilla.org/en-US/questions/1251199#answer-1199709 That code might need to be updated for Firefox 76: https://support.mozilla.org/questions/1283835

Okay, did some digging around. Found a good website that explained the location. Then I looked for similar location in Firefox Portable.

autoconfig.cfg goes here:

FirefoxPortable > App > firefox64

autoconfig.js goes here:

FirefoxPortable > App > defaults > pref

And it works!!!! Thank you so much jscher!!!! I'll try to remember the new workaround when 76.0 goes out.

ALL CREDIT AND APPRECIATION GOES TO JSCHER2000!!!

Hi gaveitatry, for the first file, can you find this folder:

[portable]\App\Firefox\defaults\pref

That seems like the equivalent of:

C:\Program Files\Mozilla Firefox\defaults\pref

The second file usually goes into the same folder as firefox.exe.

I think it's worth asking on the Portable forum if you don't get a solution here:

https://portableapps.com/forums/support/firefox_portable

Sorry, when I say "the first file" I mean the one that points to the file with the actual code in it.

Ref. Customize Firefox using AutoConfig

Actually, UPDATE:

I thought that this was the solution, but I ran into some problems. If I restart Firefox and then open up the new tab, it does go to the Chrome bookmarks page. It will let me drag bookmarks around too. But if I try to create a new bookmark there, it won't let me. And trying to create a new bookmark there will kinda break the page. It's also annoying because as soon as the new tab opens, the cursor is in the URL bar. On other websites, I actually prefer auto focus in URL bar. But not on the Chromes bookmarks page. So I guess I'll go back to just using a regular website for the new tab URL.

But maybe I'll try this again some other time, especially if I decide on another page besides Chrome bookmarks. In the future, I hope I figure out how to set the new tab title too.

Anyway, thank you.

EDIT: Turns out, it's a problem with the Chrome bookmarks page and nothing to do with this new tab URL workaround.

Yes, the bookmarks sidebar page doesn't have full functionality outside of the sidebar.

There is at least one extension that puts your bookmarks in the new tab, i.e., using the normal API for extensions to access bookmarks. I can't recall the name.