src/vs/workbench/contrib/comments/browser/commentThreadHeader.ts/CommentThreadHeader/constructor
class CommentThreadHeader:	constructor(
		container: HTMLElement,
		private _delegate: { collapse: () => void },
		private _commentMenus: CommentMenus,
		private _commentThread: languages.CommentThread<T>,
		private _contextKeyService: IContextKeyService,
		private instantiationService: IInstantiationService
	) {
		super();
		this._headElement = <HTMLDivElement>dom.$('.head');
		container.appendChild(this._headElement);
		this._fillHead();
	}