[Overlay Test] Some additional tips on tooltip & branch values default like in 2up

Just as title says
![screen shot 2014-12-19 at 1 48 00 pm](https://cloud.githubusercontent.com/assets/8551049/5511660/709e9e96-8785-11e4-84cb-9953c7305ee8.png)

Possibly do something like this?

Hotkeys: (Maybe in bold or underline)
1 - Show only the first branch
2 - Show only the second branch
3 - Show both overlaying on each other

Problem is that is starts to clutter the help tooltip, but I think this is ok(?)