The list of tags should be sorted alphabetically.

While searching for a tag to add to a post, the list should have every tag in it so that you can scroll the whole list.

While searching for a tag, it should not be case sensitive (e.g. if I search with the query "vor" it should show the tag named "Vorlage" - which currently doesn't show up).

Additionally the list should contain only tags which have not been added to the post yet.