XF 1.5 How do I make nav menu drop-down fire on click rather than hover?

Stuart Wright

Well-known member
I have a custom user field which allows members to choose whether the menu is fired on click or hover.
It works for our custom menu items, but not for the standard Xenforo menu items.
How do I customise the template(s) to fire the drop-down menu on click rather than hover, please?