Tracking selection change in the menu

[naquad]

Hi,

So I'm trying to implement a somewhat tricky behavior requiring information if the selection was changed. I.e. when the menu opens there's a pre-selected item, the user selects another item, then changes their mind and returns back to the pre-selected item.

To do this I'm trying to subscribe to view's event change but it looks like I don't understand something about those events or their handling. Here's my try:

local moved = false
cmp.event:on('menu_opened', function(evt)
  evt.window.event:on('change', function()
    print('IN!')
    moved = true
  end)
end)

IN! doesn't show up. So how do I detect new selection?