Show expandable/collapsable categories (default= all categories collapsed)

I have installed a tried nearly all of the plugins that allow you to show categories in a widget with nice expandable/collapsable effects. They are excellent for people with large amounts of categories/subcategories. I particularly like ‘Collapsing Categories’.

I have a very minimal style website. I want to collapse all by default, so that when people see the blog there is a little link that says ‘categories’. When they click that, all top-level categories are expanded.

Is this possible?

Thank you.
Kit