isCapturableWindow

Whether this window is one the capture should instrument.

Only UIWindowLevelNormal carries app content. UIKit puts the keyboard, alerts and the status bar in their own higher-level windows, and those fire the same visibility notification the install path listens to. Attaching there would at best waste a walk on a tree with no app content in it, and at worst report a tap on a keyboard key as an app interaction.

A gesture recognizer only ever sees touches delivered to the window it is attached to, so this is also why the keyboard's own taps stay invisible to the capture — measured: an on-device probe attached only to the normal-level window saw nothing at all from taps on the keyboard.