3 controls on the tree – select, expand, open

We have a tree with one click to select and double click to expand. This works well for our users and is something that would be better to keep unchanged.

Now we need to add another action to some of parent elements - to open this parent's content in a new window (this contains not only child elements, but also additional info about the parent). What could be the best option for this?

Considered solutions:

A) Add "open" to the action bar - not ideal, because an action which is detached from its object may be not obvious and users may not look at the action bar.

B) Add a button on the parent element - if add it on every element it will be too many buttons. Maybe add to only the selected one, then the question is where to place it.