Internet Explorer's transitions

With Microsoft Internet Explorer you can use filters to add special animation effects to your menu (other browsers will silently skip these effects):

sub:[
    {levelFilters:[ 'progid:DXImageTransform.Microsoft.Pixelate(duration=0.3)',
        'progid:DXImageTransform.Microsoft.Fade(duration=0.3)' ]},
    {code:'Item 1'},
    {code:'Item 2'},
    {code:'Item 3'}
]

In the sample above two animations were specified: "Fade" for "out to over" state transition, and "Pixelate" for "over to out" state transition. If you're going to use same animation for both transitions, you can use a short notation:

sub:[
    {levelFilters:'progid:DXImageTransform.Microsoft.Fade(duration=0.3)'},
    {code:'Item 1'},
    {code:'Item 2'},
    {code:'Item 3'}
]

Transitions can be combined with filters.

For more information on filters and transitions, please read this article at MSDN: Introduction to Filters and Transitions.