No clear instructions but promising Rated 4 out of 5 stars
It took me 25 minutes to figure out what this does. There are no clear instructions at the download site. You need to hold down the forward or back buttons at the upper left corner. Your history for the tab appears and, if there's a subtree, there will be an icon to the right of one or more of the entries. If you cursor over it, you can see the subtree and maybe another subtree. If there are no subtrees, you see the normal history list.
It's a neat enough idea. The app has some promise, and I will have to tell over time whether it's useful to me. It works.
This isn't the first time I've found an app and couldn't tell how to use it. App developers need to give users better guidance. If I wasn't patient, I would have tossed this 20 minutes ago and given it a 1 star rating.