The gallery will be blown up at some point and reworked. Ill keep it in mind to not force it into full screen without your permission as I bet other users will carry the same belief. Ill probably mimic a new UI where it will brief you that it will happen before hand.
That's not a hitbox issue, that's a focus issue which is unsolvable by me (Technical Limitation). The first click regains the focus of the item, the second is actually performing the task tied to it.