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Cancellation of Windows Runtime activities is asynchronous

The Windows Runtime cancellation model is asynchronous: calling cancel merely signals the request and returns immediately, without waiting for the operation to actually stop.

Background

- This post is from *The Old New Thing*, a long-running blog by **Raymond Chen** (a senior Microsoft engineer) that digs into Windows internals and quirks. - The **Windows Runtime (WinRT)** is Microsoft's modern API framework for building Windows apps (UWP, WinUI, etc.). - Key point: Cancellation in WinRT is *asynchronous* — when your code requests a cancellation (via a `CancellationToken`), the operation doesn't stop immediately. Instead, the system acknowledges the request and the operation stops *later*, when it gets around to it. You cannot assume the work is done just because the cancellation call returned. - This matters because developers often write sequential code expecting synchronous cancellation, leading to subtle bugs where resources are still in use or callbacks fire after the "cancelled" state is entered.

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