I created a page that has a JQuery based dialog using the standard JQuery UI function. I do this with out of the box functionality of JQuery... nothing special at all. Here
If you're using a "popup" rather than a "dialog" I had to do the following:
HTML
CSS
.popup { display:none; } .ui-popup-container .popup { display:block; }
I initially hide the popup using display:none and after jQueryUI wraps the popup in a container, the other style takes precedence.