Show tag button when creating or editing a gist

[chaoscreater]

I have a lot of tags and I can't always remember the name of the tags. When I'm creating or editing a gist, I would like to be able to choose and assign tag(s) to the gist. At the very least, I would like for a button to see my current list of tags. There is already a tag button next to the search field, but this button isn't available when you're creating or editing gists.

[sanusart]

All existing tags available at the searchable dropdown: