Math formulas can not display in headlines.

[shanhaiying]

Math formulas can not display in headlines if the LaTeX_envs activated.

The result is ：

when the LaTeX_envs deactivated the result is:

[jfbercher]

Thanks. Good spot. I can reproduce. It seems that something has changed between notebook 4.2 and 4.3 in the sanitize_html step. A quick fix is just to exchange two lines in the MarkdownCell.prototype.renderin latex_envs.js to read

                html = security.sanitize_html(html);
		html = thmsInNbConv(marked, html); //<----- thmsInNb patch here

I will fix that shortly (but I have also some other little things to include).

[shanhaiying]

I have tried to fix this as you suggest. I find it is not always effective.
If there are some code cell changed to text cell, then the math formulas in headlines will disappear again until the page is refreshed.

[jfbercher]

Sorry, I can not reproduce. Can you describe step by step the scenario?

[shanhaiying]

The following screencap show what happen. But I can not reproduce it every time.

[jfbercher]

Actually, I think that this is a rather involved issue involving an interaction between latex_envs and toc2: toc2 copies the headers into links in order to populate: the toc2 widow/sidebar, the table of contents (if enabled) in the notebook, the navigate menu. When latex_envs is enabled, it has the capability to keep all equations and environments correctly numbered: each markdown rendering entails the reset of all equations nubers and the recomputation of all math renderings. Maths are stored as a preview in html, with styling, classes, ids, end embedded scripts. When copying the headers into links, these previews are copied as well. The duplication of ids than cause a mess to the webpage rendering: maths in the toc window/sidebar is sometimes duplicated, maths can disappear in the toc and/or in the navigation menu.
I have made a PR to jupyter_contrib_nbextensions to remove mathjax previews when creating links in toc2. This has also the advantage of restoring a simpler html source (see the toc_cell source for instance).