Event 2 always sets Event 3 true.
Its is not so that the 'on tap' in event 2 steals the 'on tap' in event 3.
They are triggers. Triggers fire when that event, what they are designed to catch, happens.
Every condition that starts with 'on' is a trigger.
So if you have a thousandth 'on tap gesture', they all trigger when the 'tap' happens. And since you make event 3 always true (by setting the layer visible in event 2, and by having a fullscreen button), event 3 will trigger always when event 2 triggers.
Tinkering about a solid solution for you.