Gtk::MenuButton and widget selection

Hi, I’m using gtkmm4, I have a Box with with a few MenuButtons.
I expected to be able to move the selection using the arrow keys, but I can’t.
For test, I tried adding a “regular” button to the box, and the arrows keys worked fine.
I would like to implement the same behavior for the MenuButtons, how can I do that?
What signal should I use? What method I should connect to select a MenuButton?