I believe what you want for your horizontal menu is probably a menubar, which we had started working on, but decided to put on hold. See the
planning page and the
menubar branch for more details.
I have no idea what a spoiler widget is.
It sounds like you're probably not adhering to any of the jQuery UI standards, and we don't allow external plugins to become part of jQuery UI anymore. All plugins must start new, following our standards very closely, and only after an initial design phase.