There are these two prefs available to set the fixup:

• browser.fixup.alternate.prefix
• browser.fixup.alternate.suffix

• https://support.mozilla.org/en-US/kb/search-web-address-bar

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

" I don't want to change CTRL-ENTER to shortcut .COM to .CO.UK because that shortcut is equally as useful.... (One of the problems with being British and having a nigh-on 50/50 mix of .COM / .CO.UK domains in use here). "

The settings for browser.fixup.alternate.prefix & browser.fixup.alternate.suffix affect the shortcut of CTRL-ENTER and changing them would stop CTRL-ENTER from producing WWW.somedomainname.COM - as I explained in the question, I need to keep CTRL-ENTER as WWW. .... .COM and change SHIFT-ENTER from WWW. ... .NET to WWW. ..... .CO.UK

The other modifier variants are hard coded and I'm not aware of a way to change them.

• https://dxr.mozilla.org/mozilla-release/source/browser/base/content/urlbarBindings.xml#805

I've just had a glance over the XML file you've referred to in this link https://dxr.mozilla.org/mozilla-release/source/browser/base/content/urlbarBindings.xml#805 and beginning at line 819, I see this:

         switch (true) {
           case (accel && shift):
             suffix = ".org/";
             break;
           case (shift):
             suffix = ".net/";
             break;
           case (accel):
             try {
               suffix = gPrefService.getCharPref("browser.fixup.alternate.suffix");
               if (suffix.charAt(suffix.length - 1) != "/")
                 suffix += "/";
             } catch (e) {
               suffix = ".com/";
             }
             break;
         }

Clearly the 'offending' line * suffix = ".net/"; * is there - is there any way for me to edit this and relink the browser myself???? (and every time afterwards when Mozilla updates the thing and breaks it)???

Where is this code stored exactly???

This file is located in one of the omni.ja archives (specially packed ZIP archives).

resource:///chrome/browser/content/browser/
view-source:resource:///chrome/browser/content/browser/urlbarBindings.xml

How can I find this file on my machine? And if it's find-able after downloading the "latest update" for Firefox (whenever that may be, they're ongoing)... If I know how to edit and re-install off the local (having been downloaded) sourcefiles, I can just edit the affected one and effectively apply my own patch with every update... I am not afraid to do this because although I don't know what language it (Firefox) was written in, about 30 (yes thirty) years ago, I used to code in Clipper on DOS platforms - I'm not a complete numpty... if you can tell me how to do this (or tell me where to read for myself how to do this), I'll patch it myself. I cannot emphasise enough that us Brits basically use 50/50 .COM / .CO.UK domains which means that putting up with how this has been broken makes the browser no better than all the others.... I'm not knocking the Americans who almost certainly wrote the thing - but they don't have the 50/50 .COM / .CO.UK problem.... and indeed .NET is probably of more use the other side of the pond... But the breaking of every single one of the add-ons has destroyed the advantages FF has have over Explorer, Chrome, Edge and the others - for me and lots of other Brits. I'd imagine too, this has been what's made FF our #1 preferred browser. This is so frustrating !!!!

If you open the second link then Firefox shows the actual path of the file.

• view-source:resource:///chrome/browser/content/browser/urlbarBindings.xml

• /browser/omni.ja!/chrome/browser/content/browser/urlbarBindings.xml

Any idea on what I will need to open view (and modify and save back) the .JA file?

It is a ZIP archive, but it is packed in a special way so it can be loaded as quickly as possible. You can try 7-ZIP or another archive manager.

• https://developer.mozilla.org/en-US/docs/Mozilla/About_omni.ja_%28formerly_omni.jar%29

I have 3 machines here - 1 laptop and 2 desktops. Both desktops are at V56 because of the broken URL suffix additions. I've looked through the source (on this machine) and the lines are missing - but it's only at V56. I need to download the latest patches to the laptop and 'play' with 7-zip to see whether I can edit the XML file in the source on the local hard disk. If I can and it works, I will patch the least used desktop and do it again (and document)... And if that works, I will patch this machine and leave the "what I did" for the benefit of others - along with thanking you, cor-el for your inside knowledge and help on this.... One thing I can think of before I go to bed (it is almost 3am in England now) is will it (Firefox itself) fail some sort of CRC check if I've messed with this JA archive???

Keep a copy of the original \browser\omni.ja file, so you can easily restore it.

There is this python script that you can possibly use: optimizejars.py:

• https://dxr.mozilla.org/mozilla-esr17/source/config/

optimizejars.py --deoptimize ./ ./ ./
optimizejars.py --optimize ./ ./ ./

python <path>/optimizejars.py  [--optimize|--deoptimize] <path_to_omni.jar.log> <path_to_omni.jar> <path_to_mod_omni.jar>