Pointer Focus Registration Code Direct

# 3. Notify old focus (asynchronous, allow cleanup) if old_focus and old_focus != candidate: old_focus.on_pointer_focus_lost(event)

You click a button. It highlights. You type, and text appears. It feels instantaneous, obvious, even banal. pointer focus registration code

def register_pointer_focus(candidate, event): # 1. Pre-condition: candidate is alive and hittable assert candidate.is_alive() assert candidate.hit_test(event.x, event.y) == True # 2. Invalidate current focus without releasing events yet old_focus = system.pointer_focus system.pointer_focus = None # 3. Notify old focus (asynchronous

Be the former.

Screen readers, switch devices, and eye trackers all rely on . They inject synthetic pointer events with zero physical movement. and text appears. It feels instantaneous

The best systems make pointer focus invisible. The worst make it unforgettable.