I've been playing with Mootools over the past week or so and had something that worked great during my testing on safari, camino, opera + firefox (os x versions on MacPro) IE7 and firefox 2 (windows) I've just put the site up live and am experiencing some weird behaviour with Fx.Slide in Safari (2.01 on my iBook).
Please could some users check out http://www.notely.net/demo.php (requires login with the pass provided) then click through some of the tabs, the forms should slide out of the yellow div when you click on the add link within the yellow div.
On Safari the forms aren't sliding out fully all the time, some pages are fine, some not. I've tested some browsers but can't get my hands on any more.
Thanks for any reports back!