src/vs/workbench/browser/composite.ts/CompositeRegistry/deregisterComposite
class CompositeRegistry:	protected deregisterComposite(id: string): void {
		const descriptor = this.compositeById(id);
		if (!descriptor) {
			return;
		}

		this.composites.splice(this.composites.indexOf(descriptor), 1);
		this._onDidDeregister.fire(descriptor);
	}