The plugin [description](https://github.com/geany/geany/blob/fda8b97ea634877952acc86d58b75b25537486bb...) mentions `&`, but & is explicitly not either automatically or manually replaced with the entity. Same goes for < > ; etc.
In fact all the "HTML" chars can only be inserted from the menu, none of the automatic replacements work for them, which is fair enough since they need to be able to be typed to make HTML and XML and shouldn't be replaced.
Suggestions are solicited for a better one-line description.