In Moodle 3.8 new code was added to theme/boost/amd/src/loader.js that replaces the URL with the tab name when switching to the tab.

Moodle Workplace had similar code since 3.7 but it was causing scrolling so we created a workaround. In 3.8 we are trying to use the core functionality but the page keeps scrolling.

After several hours of debugging I figured out that it is MathJax filter that causes the page to scroll.

1. Use attached test files "testtabs.php", place it in wwwroot and open in the browser
2. Click on the second tab, you will notice scrolling
3. Go to "Site aministration>Plugins>Manage filters" and disable MathJax filter
4. Go back to testtabs.php
5. Now if you click on second tab the page does not scroll
6. (Enable filter back)

Why it happens:

When we click on the second tab we want to dynamically load content, so we use "Templates.replaceNodeContents", which calls "event.notifyFilterContentUpdated(newNodes);"

MathJax filter listens to this event and tries to substitute the mathjax content. Even if there is no mathjax content in the new nodes, it still calls function "_setLocale()" which calls "window.MathJax.Hub.Configured()"

The later causes scrolling. Why? No idea. I could not find anything while googling.

If you remove this line
https://github.com/moodle/moodle/blob/master/filter/mathjaxloader/yui/src/loader/js/loader.js#L81
scrolling stops happening.

I would REALLY appreciate help on this, it's quite critical in upgrading Moodle Workplace to 3.8. Also it will become a problem for any users of bootstrap tabs in 3.8 with dynamically loaded content.