That's one of the features of V2 Beta & all the documentation hasn't been written for it as yet.
There is info about it within the Forum & also on Pete's Page here:
Hi Mark, yup check out the very top of the page that Colin linked to for some description of how it works, look for the part that mentions "Edit frame".
I'm right on the verge of finishing up the software part for v2. Once the software is all wrapped up then I'll be working on updating the documentation for new v2 features like this.