Make headings selectable

[josevalim]

Closes #1969.

[josevalim]

@DavidOliver, this was added in 3189db6, so I am pinging you to see if you are happy with this revert. :)

[DavidOliver]

@josevalim, thanks. This seems to result in the hover link for the fragment only showing when it itself is hovered, and not when the heading is hovered, which I think is not ideal.

Shall we aim for the hover link to show when either the heading or the hover link is hovered, but to leave the heading selectable, requiring pointing to the hover link icon itself to use the fragment link? I can have a look at doing that if there is agreement.

[josevalim]

Great catch!

Shall we aim for the hover link to show when either the heading or the hover link is hovered, but to leave the heading selectable, requiring pointing to the hover link icon itself to use the fragment link? I can have a look at doing that if there is agreement.

Yes, please!