Xamarin Test - Click on setting button in toolbar

I'm using Xamarin to test my Android application and i want to click on the setting button in the toolbar. The problem is that this toolbar is an android.support.v7.widget.Toolbar and the setting button is embedded in this widget. Indeed, when i'm using REPL to display the elements and find mine, if i Flash the action bar i get this:

Flashing query for Id("action_bar") gave 1 results.

[
    [0] {
        Id => "action_bar",
        Description => "android.support.v7.widget.Toolbar{....app:id/action_bar}",
        Rect => {
            Width => 1080,
            Height => 168,
            X => 0,
            Y => 72,
            CenterX => 540,
            CenterY => 156
        },
        Label => null,
        Text => null,
        Class => "android.support.v7.widget.Toolbar",
        Enabled => true
    }
]

Nothing about that setting button.

Do anyone know how i can find and click on that setting button ? Thank you !