User blog comment:Kirkburn/Technical Update: October 26, 2015/@comment-25050081-20151029095421/@comment-168424-20151029212112

The syntax highlighting preference should not be used for this. Syntax highlighting worked fine in the previous source editor. You shouldn't have to switch editors to enable syntax highlighting.

Also the new editor doesn't just do syntax highlighting. It has strange selection problems, requires a separate find/search, and unhelpfully inserts close tags in the wrong place all the time.