src/vs/workbench/api/browser/mainThreadNotebookEditors.ts/MainThreadNotebookEditors/_updateEditorViewColumns
class MainThreadNotebookEditors:	private _updateEditorViewColumns(): void {
		const result: INotebookEditorViewColumnInfo = Object.create(null);
		for (const editorPane of this._editorService.visibleEditorPanes) {
			const candidate = getNotebookEditorFromEditorPane(editorPane);
			if (candidate && this._mainThreadEditors.has(candidate.getId())) {
				result[candidate.getId()] = editorGroupToColumn(this._editorGroupService, editorPane.group);
			}
		}
		if (!equals(result, this._currentViewColumnInfo)) {
			this._currentViewColumnInfo = result;
			this._proxy.$acceptEditorViewColumns(result);
		}
	}