jQuery: Does toggleClass no longer have a duration?

I can't get the duration setting on toggleClass to actually do anything.

I'm running jQuery 1.4.4 and jQuery UI 1.8.7.

jQuery's own example page of using duration doesn't wo开发者_运维知识库rk for me: http://jqueryui.com/demos/toggleClass/default.html

Clicking "Run Effect" literally does nothing in both Safari and Firefox 3.6 on Mac for me.

Anyone have some insight on this?