src/vs/platform/quickinput/browser/quickInput.ts/QuickInputService/setContextKey
class QuickInputService:	private setContextKey(id?: string) {
		let key: IContextKey<boolean> | undefined;
		if (id) {
			key = this.contexts.get(id);
			if (!key) {
				key = new RawContextKey<boolean>(id, false)
					.bindTo(this.contextKeyService);
				this.contexts.set(id, key);
			}
		}

		if (key && key.get()) {
			return; // already active context
		}

		this.resetContextKeys();

		if (key) {
			key.set(true);
		}
	}