jQuery UI Tabs - Available fx options
Basically the fx option is used to call animate, you can specify a single option or two in an array, that will be used to do the show and hide effects:
$('#tabs').tabs({ fx: [{opacity:'toggle', duration:'normal'}, // hide option {opacity:'toggle', duration:'fast'}] }); // show optionThe fx speed can be specified using a duration member on the option object.
Basically you can do the same transformations that you can with animate.
Give a look to the ui.tabs.js file, on the line 250 here, to understand better how the animations are setup.