Created attachment 271274 [details]
accessible-event listener

Steps to reproduce:
1. Launch gtk3-demo master
2. Launch the popover demo
3. Launch the attached accessible event listener in a terminal*
3. Press space on the "Button" button to show the popover
4. Press space on the "Button" button to hide the popover

Expected results: An object:state-changed:showing event would be emitted when the popover is shown or hidden.

Actual results: The only object:state-changed events emitted are by the button, which emits signals for the checked and armed states:

object:state-changed:checked(1, 0, 0)
	source: [toggle button | Button]
	host_application: [application | gtk3-demo]
object:state-changed:armed(1, 0, 0)
	source: [toggle button | Button]
	host_application: [application | gtk3-demo]
object:state-changed:armed(0, 0, 0)
	source: [toggle button | Button]
	host_application: [application | gtk3-demo]
object:state-changed:checked(0, 0, 0)
	source: [toggle button | Button]
	host_application: [application | gtk3-demo]

Impact: Orca presents nothing in reaction to the appearance of the popover because the expected state-changed:showing event is missing and the popover doesn't grab focus.

* Note: if you are running gtk3-demo in a jhbuild shell, you need to run the listener in a jhbuild shell due to some recent changes within AT-SPI2.