I wanted to post this a couple days ago when the problem was brought to my attention at a forum I code for, but was too busy to get it up until now. The problem has a fix for it, here. I just want to go over quickly what is the cause of the problem and let people know it may effect Chrome and Opera. The fix was simply changing some variable names, so it wasn't anything too complicated.
So Firefox implemented something called Microdata API. This is a new thing for HTML5 that adds more information to your markup. The catch is, whether or not you are using HTML5, it still effects your site. It adds new DOM attributes that MyBB 1.6.8 is using. This particular one is itemData. That is now an object and due to the way the script was made for the post editor, it just screws it up. From what I've read, Chrome and Opera will be implementing them soon. I hope eventually it will be made to only effect HTML5 pages.
I have yet to read up how to use the Microdata API, but if you are interested, you can find notes on it here.
So Firefox implemented something called Microdata API. This is a new thing for HTML5 that adds more information to your markup. The catch is, whether or not you are using HTML5, it still effects your site. It adds new DOM attributes that MyBB 1.6.8 is using. This particular one is itemData. That is now an object and due to the way the script was made for the post editor, it just screws it up. From what I've read, Chrome and Opera will be implementing them soon. I hope eventually it will be made to only effect HTML5 pages.
I have yet to read up how to use the Microdata API, but if you are interested, you can find notes on it here.