Markdown headings #title (with no space)

[tritemio]

Since switching to jupyter notebook 4 the markdown heading that don't have a space between # and the title string do not render as headings anymore.

Is this a deliberate change? Should we start updating all out notebooks using a space between # signs and actual title?

[Carreau]

This is a changed in the underlying library to fix a bug as in the markdown spec the is a space after the hash.

[Carreau]

duplicate of #276 and jupyter/jupyter#16

[tritemio]

Thanks for the info. I understand the principle, but it will be painful to update notebooks everywhere :-/.

[tritemio]

@Carreau, as you mention in the duplicated issue, a tool (extension adding a menu entry?) to automatically fix notebooks would be quite useful.

[Carreau]

On 4.1 you will be able to select search and replace, enable reg-ex and search ^(#+)([^ ]) replace by $1 $2.

[tritemio]

Great, awesome! Worth adding it to the migrating to 4.x section of the docs.

[tritemio]

@Carreau, I would like to send a PR to add to the docs a section of UI changes in the notebook 4.x.

For now it will contain the info in this issue and the new shortcuts to select and merge multiple cells (I initially though the merge shortcut was broken).

Which repo should I target, notebook or the main jupyter docs at:

http://jupyter.readthedocs.org/en/latest/migrating.html#migrating-from-ipython

I would prefer adding only a link in the previous page and a new section in the notebook docs.

[sebastien-bratieres]

I guess the regex to match should not be ^(#+)([^ ]) but ^(#+)([^ #]) (otherwise, in case of headings of level 2 and more, the last # will match the second group).