src/vs/workbench/electron-sandbox/window.ts/NativeWindow/onWillShutdown
class NativeWindow:	private onWillShutdown({ reason, force }: WillShutdownEvent): void {
		this.progressService.withProgress({
			location: ProgressLocation.Dialog, 				// use a dialog to prevent the user from making any more interactions now
			buttons: [this.toForceShutdownLabel(reason)],	// allow to force shutdown anyway
			delay: 800,										// delay so that it only appears when operation takes a long time
			cancellable: false,								// do not allow to cancel
			sticky: true,									// do not allow to dismiss
			title: this.toShutdownLabel(reason, false)
		}, () => {
			return Event.toPromise(this.lifecycleService.onDidShutdown); // dismiss this dialog when we actually shutdown
		}, () => {
			force();
		});
	}