src/vs/workbench/services/editor/browser/editorService.ts/EditorService/registerGroupListeners
class EditorService:	private registerGroupListeners(group: IEditorGroupView): void {
		const groupDisposables = new DisposableStore();

		groupDisposables.add(group.onDidModelChange(e => {
			this._onDidEditorsChange.fire({ groupId: group.id, event: e });
		}));

		groupDisposables.add(group.onDidActiveEditorChange(() => {
			this.handleActiveEditorChange(group);
			this._onDidVisibleEditorsChange.fire();
		}));

		groupDisposables.add(group.onDidCloseEditor(e => {
			this._onDidCloseEditor.fire(e);
		}));

		groupDisposables.add(group.onDidOpenEditorFail(editor => {
			this._onDidOpenEditorFail.fire({ editor, groupId: group.id });
		}));

		Event.once(group.onWillDispose)(() => {
			dispose(groupDisposables);
		});
	}