src/vs/workbench/contrib/notebook/browser/notebookEditorWidget.ts/NotebookEditorWidget/onWillHide
class NotebookEditorWidget:	onWillHide() {
		this._isVisible = false;
		this._editorFocus.set(false);
		this._overlayContainer.style.visibility = 'hidden';
		this._overlayContainer.style.left = '-50000px';
		this._notebookTopToolbarContainer.style.display = 'none';
	}