How to open the form view from a tree view with field_parent (like Chart of Accounts) ?

I'm trying to make an action to open a form view from a tree, with children. By looking into the code, I found that I have to use an action with `key2="tree_but_open"`. So I try the following action: I also found the "Action creation - Linking events to action" documentation, but I don't know how to use it in my case. Can you help me ?