src/vs/workbench/contrib/notebook/browser/contrib/outline/notebookOutline.ts/NotebookCellOutline/_recomputeActive
class NotebookCellOutline:	private _recomputeActive(): void {
		let newActive: OutlineEntry | undefined;
		const { viewModel } = this._editor;

		if (viewModel) {
			const cell = viewModel.cellAt(viewModel.getFocus().start);
			if (cell) {
				for (let entry of this._entries) {
					newActive = entry.find(cell, []);
					if (newActive) {
						break;
					}
				}
			}
		}
		if (newActive !== this._activeEntry) {
			this._activeEntry = newActive;
			this._onDidChange.fire({ affectOnlyActiveElement: true });
		}
	}