Disabled items are selectable using the keyboard

Please see the following jsbin: https://output.jsbin.com/womaci

Initially I wanted to create a header. Being able to create a header appears to have been possible in older versions: http://jsfiddle.net/IrvinDominin/rMkER/

When I added a header I found it was selectable. I could override the mouse events but not the keyboard. I found a solution which suggested I could use "ui-state-disabled" as specified in the menu widget documentation. I attempted to create a disabled header item in the hope it would skip selecting the header. This is when I found a secondary issue where disabled items can be selected via the keyboard.

Also I don't believe it should be possible to select disabled items using the keyboard. This may be a problem with the menu widget but looking a the source it appears the autocomplete implementation is not respecting the menu implementation.