src/vs/workbench/contrib/notebook/browser/contrib/cellStatusBar/notebookVisibleCellObserver.ts/NotebookVisibleCellObserver/_onModelChange
class NotebookVisibleCellObserver:	private _onModelChange() {
		this._viewModelDisposables.clear();
		const vm = this._notebookEditor.viewModel;
		if (vm) {
			this._viewModelDisposables.add(vm.onDidChangeViewCells(() => this.updateEverything()));
		}

		this.updateEverything();
	}