I was having problems tabbing through my new form. I found this post, which led me in the right direction: http://www.gravityhelp.com/forums/topic/tab-index-on-fields-are-acting-wierd
The tabbing problem was not another form in a widget, however. The WordPress Admin bar also uses tabindex, apparently for reasons of accessibility. Here is the reference link:
To me, rather than asking users of your software to change the tabindex of all other forms in use at their sites, I think it would be more appropriate for Gravity Forms to allow us to define a tabindex for the fields in our forms, especially since I've learned tonight that the conflict is in a tabindex set on a core feature of WordPress itself. I had to chase a lot of code around to remedy the issue and this seems unnecessary. If I had created a form from scratch, I could have easily declared the tabindex of the form fields to begin AFTER the tabindex of the core WordPress Admin Bar.
What are your thoughts on this?