Pointer Focus Registration Code File

Welcome to the world of . It’s not glamorous. But if you get it wrong, your users will feel it. What Is Pointer Focus, Really? Let’s kill the high-level abstraction immediately.

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 pointer focus registration code

is the exclusive right of a single UI element to receive input events originating from a pointing device (mouse, pen, touch). Unlike keyboard focus (which can be transferred via Tab ), pointer focus is transient, aggressive, and inherently tied to geometry and z-order. Welcome to the world of