NativeKeyCodeExtensions
ABI companion for NativeKeyCode. The enum's integer values are mirrored in the native plugin sources (macOS/iOS.mm, WebGL.jslib, Android.java) — when a key is appended to the enum, update MaxDelivered and the native tables together (see Additional/plans ci-checks.md for the sync invariants).
Whether a raw key value from a native boundary is a real, deliverable key: in range and not the NativeKeyCode.None sentinel.
public static bool IsLetter(NativeKeyCode key)Whether the key is a letter (A–Z). Letters are delivered as KeyDown only when Ctrl/Cmd is held — a bare letter press is text (it arrives via TextInput), never a shortcut, on every backend.
public static const NativeKeyCode MaxDeliveredHighest key value the platform layer may deliver. The single receiver-side clamp — individual backends must never hardcode their own upper bound (a stale per-backend clamp silently mutes keys appended later).