[DMcCunney]

I expect to see more Firefox issues popping up here, so background is in order.

I've used Mozilla code since Mozilla was still the code name for a Netscape project to create the next generation browser suite, replacing the venerable Netscape Communicator 4, which was getting long in the tooth.

Instead of refactoring and enhancing the existing proven and debugged code base, Netscape chose to "throw out the baby with the bathwater", and start from scratch with a new code base. (I understand the decision was made by a VP who was not technical, and did not grasp what he was asking for, but he was the VP, so...)

Two years passed with no sign of development. We finally got a Netscape 6, bypassing 5 entirely. It was so buggy as to be unusable. As far as I could tell, the only reason it got released was to demonstrate development was occurring.

Eventually we got Netscape 7, which was usable, and I ran it for a while.

In the meantime, Netscape was bought by AOL, and the Mozilla project was cancelled and most of the developers were laid off. The code base and the servers the work was done on were transferred to the newly created Mozilla Foundation, with a couple of million in seed funding, and development continued under Mozilla. Mozilla decided most folks only wanted a browser, and the browser component of what was then the Mozilla Suite was broken out and became Firefox.

Mozilla products all used a new rendering engine called Gecko. Gecko understood and rendered HTML and CSS, and interpreted and ran JavaScript. It also understood and rendered XUL, an XML language intended for writing user interfaces. The "look-and-feel" of Mozilla products was provided by XUL, CSS, and widgets, with JavaScript doing the work when you clicked on something. If you were proficient in XUL, you could create themes that completely altered the way the products looked, and extensions that modified and extended the way the products worked.

Mozilla seems not to have learned from history. Firefox 57 uses a new rendering engine called Quantum, written in a whole new language Mozilla has been developing called Rust. They threw out the baby with the bathwater again.

The sort of things you used to do with Themes are no longer possible, and haven't been for some time. Current themes are lightweight decorations of the title bar.

Most existing extensions have simply stopped working. They were written in XUL and JaaScript, and XUL no longer exists. New extensions must be entirely JavaScript, using the Web Extensions API, and limited to what WebEx will let JavaScript do.

The good part is that it's possible to write extensions that can be installed in Google Chrome and MS Edge with minor code changes, because they support a similar model. The bad part is that a lot of things people were accustomed to being able to do with extensions can't be done in WebEx.

As mentioned, I reverted to Firefox ESR, where what I need it still supported, with a test profile in Firefox Developer Edition using only WebEx stuff to track progress.

The problem is that the changes Mozilla is making have largely removed all the reasons I ran Firefox in the first place. I didn't use it because it was more secure than others (though it was.) I used it because it was the most powerful browser. That power is being neutered in the name of security. The question is presents is why bother to run Firefox at all? Just give up and switch to Chrome, because there is increasingly little difference in looks or operation.

Firefox's share of the browser market has been steadily declining because a lot of other folks asked the same question and switched, but I've seen no evidence Mozilla has drawn any conclusions from it.

If you are just running vanilla Firefox without extensions, you won't see problems. If, like me, you make any extensive use of extensions, you'll have problems, and the above is why.
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Dennis