datepicker: fixes #3679 [focus error on IE if disabled]: added visual test to verify. Both IE 6 & 7 do not return an error.
datepicker: fixes #3679 [focus error on IE if disabled]: added visual test to verify. Both IE 6 & 7 do not return an error.

GrayYoung/jQuery.UI.Extension,GrayYoung/jQuery.UI.Extension