PopupMenu id_focused signal

I'm trying to do something when a PopupMenu item is focused (mouse hover).

The docs say that the id_focused signal is "Emitted when user navigated to an item of some id using ui_up or ui_down action."

I've tried this and the signal doesn't seem to be firing when I navigate using those actions or mouse hover.

Am I missing something?

I made a mistake. The signal does fire using the ui_up and ui_down actions. But is there any way to get the item under the mouse?