Automatic linking annoyance
The editor is too trigger happy to automatically mark anything that looks like links to appear as links. E.g. typing somefile.sh becomes linked w/o asking. It's very annoying when trying to type or paste code snippets that has fragments looking like that and removing them is quite troublesome :\
Edit: Links can be removed after they've been inserted by editor, but this leaves extra unused garbage html, and that can be removed by editing hidden textarea using browser developer tools and not directly interacting with text field thus avoiding accidental reinsert of link where it is not wanted.