We're currently developing a site for a client (so I can't link to it - sorry!) and we've found that Firefox users are suffering many javascript related issues when trying to Preview pages. We see multiple 'window.getComputedStyle returns null' errors. Also, modernizr seems to create a second 'body' node for it's testing, presumably because of the slow loading of the actual body content. Finally, we have also noticed that clicking the 'Preview' button occasionally deletes some of the custom data from our documents, almost as if the data loading wasn't complete before the Preview button was displayed. All this only seems to happen when using Firefox (latest version). Does anyone else experience similar issues, know of any fixes? Many thanks!