Catagories widget collapse?

Hi Guys,

I like the categories widget at the side of my pages as its a useful search tool for users. But it doesn’t collapse despite looking like a ‘plus’ sign? On most sites I can think of you can expand a catagory with a click and clicking back on the same category will collapse it, as would clicking on another category.

With the current setup it actually reloads the whole page which feels really odd.

Is there a setting or is there a plugin that might help?

Thanks

Mark