I'm testing with 1460 here. The page is unbearably slow in IE but not too bad in other browsers. However, what your screenshot shows is the JS not being initialized yet. With a slow downloading page and a browser that renders incrementally, that could definitely happen here -- the page is about 3.4 MB! Once the page loads, all of the popups are initialized and it works fine for me.
I may try to shrink the size of the page, but the underlying behavior (JS initialized when all HTML is downloaded) is as designed.
I'm also not too happy with the current beta as when you've added a new node, you're now directed back to the node list which again takes forever to load. Whereas the last beta you could add a new forum and it would stay on the same page, this was better for me.