The doorhanger is dismissed because of the navigation event (specifically whenever the "content finished loading" event fires and we find out we're on a different origin, which happens to coincide with that overlay loading). This behavior is intended, when the user gets the doorhanger:
- The doorhanger is not dismissed by clicking anywhere in the content or browser UI
- The doorhanger is only dismissed by interacting with one of the two buttons
The navigation event is interpreted as dismiss.
For our "softer" doorhangers (the ones that can be dismissed simply by clicking anywhere on the current page) we set a limit of 3 impressions and separate them at least 24hrs apart. That way we're sure the user had sufficient opportunities to see and interact with the doorhanger.