I did not change anything important.
All the class/div names, all variables etc. are the same.
I just wrote instead of "Create new user", "add". Stuff like that.
But the whole thing works perfectly on chrome, mozilla.
With autoOpen: false, it works fine on all browsers apart from IE.
In IE the #dialog-form is always there (not as a pop-up) when the page loads.
With autoOpen: true, the pop-up shows up on page load on all browsers apart from IE again...