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:

<act_window
        id="my_action"
        name="My Action"
        res_model="my.object"
        src_model="my.object"
        res_id="active_id"
        view_type="form"
        view_mode="form,tree"
        key2="tree_but_open"/>

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 ?