I found a real problem with highlight and only highlight (I have not test all the jQuery UI effects but those which I tested works) and I really don't understand where the problem is.

I made a little page for you to test the problem :  francois.robichet.com/highlight/

If the input is filled, you gonna have a big green "Ok" will appear at its right.

If it's empty, it's gonna be a big red "Requis" (require in French).

You have 2 buttons, one wich use effect('highlight') after it check if the input is empty, the other one doesn't use effect('highlight').

(In fact, it's a form and I want to show to users where did they do mistakes by higlight the red thing).

If you test it, you can see that the highlight change the span to display: inline and I really don't want that :(

Thanks :)