diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 23519cda472..ee7d648885b 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -1829,8 +1829,6 @@ declare module 'vscode' {
 		 * All currently known notebook documents.
 		 */
 		export const notebookDocuments: ReadonlyArray<NotebookDocument>;
-
-
 		export const onDidChangeNotebookDocumentMetadata: Event<NotebookDocumentMetadataChangeEvent>;
 		export const onDidChangeNotebookCells: Event<NotebookCellsChangeEvent>;
 		export const onDidChangeCellOutputs: Event<NotebookCellOutputsChangeEvent>;
diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index f5a77b55ceb..9c6a45defee 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -949,7 +949,15 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 		};
 
 		// namespace: notebook
-		const notebook: typeof vscode.notebook = {
+		const notebook: (typeof vscode.notebook & {
+			// to ensure that notebook extensions not break before they update APIs.
+			visibleNotebookEditors: vscode.NotebookEditor[];
+			onDidChangeVisibleNotebookEditors: Event<vscode.NotebookEditor[]>;
+			activeNotebookEditor: vscode.NotebookEditor | undefined;
+			onDidChangeActiveNotebookEditor: Event<vscode.NotebookEditor | undefined>;
+			onDidChangeNotebookEditorSelection: Event<vscode.NotebookEditorSelectionChangeEvent>;
+			onDidChangeNotebookEditorVisibleRanges: Event<vscode.NotebookEditorVisibleRangesChangeEvent>;
+		}) = {
 			get onDidOpenNotebookDocument(): Event<vscode.NotebookDocument> {
 				checkProposedApiEnabled(extension);
 				return extHostNotebook.onDidOpenNotebookDocument;
@@ -966,6 +974,14 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				checkProposedApiEnabled(extension);
 				return extHostNotebook.notebookDocuments.map(d => d.notebookDocument);
 			},
+			get visibleNotebookEditors(): vscode.NotebookEditor[] {
+				checkProposedApiEnabled(extension);
+				return extHostNotebook.visibleNotebookEditors;
+			},
+			get onDidChangeVisibleNotebookEditors() {
+				checkProposedApiEnabled(extension);
+				return extHostNotebook.onDidChangeVisibleNotebookEditors;
+			},
 			get onDidChangeActiveNotebookKernel() {
 				checkProposedApiEnabled(extension);
 				return extHostNotebook.onDidChangeActiveNotebookKernel;
@@ -984,6 +1000,14 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 			createNotebookEditorDecorationType(options: vscode.NotebookDecorationRenderOptions): vscode.NotebookEditorDecorationType {
 				return extHostNotebook.createNotebookEditorDecorationType(options);
 			},
+			get activeNotebookEditor(): vscode.NotebookEditor | undefined {
+				checkProposedApiEnabled(extension);
+				return extHostNotebook.activeNotebookEditor;
+			},
+			onDidChangeActiveNotebookEditor(listener, thisArgs?, disposables?) {
+				checkProposedApiEnabled(extension);
+				return extHostNotebook.onDidChangeActiveNotebookEditor(listener, thisArgs, disposables);
+			},
 			onDidChangeNotebookDocumentMetadata(listener, thisArgs?, disposables?) {
 				checkProposedApiEnabled(extension);
 				return extHostNotebook.onDidChangeNotebookDocumentMetadata(listener, thisArgs, disposables);
@@ -992,6 +1016,14 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				checkProposedApiEnabled(extension);
 				return extHostNotebook.onDidChangeNotebookCells(listener, thisArgs, disposables);
 			},
+			onDidChangeNotebookEditorSelection(listener, thisArgs?, disposables?) {
+				checkProposedApiEnabled(extension);
+				return extHostNotebook.onDidChangeNotebookEditorSelection(listener, thisArgs, disposables);
+			},
+			onDidChangeNotebookEditorVisibleRanges(listener, thisArgs?, disposables?) {
+				checkProposedApiEnabled(extension);
+				return extHostNotebook.onDidChangeNotebookEditorVisibleRanges(listener, thisArgs, disposables);
+			},
 			onDidChangeCellOutputs(listener, thisArgs?, disposables?) {
 				checkProposedApiEnabled(extension);
 				return extHostNotebook.onDidChangeCellOutputs(listener, thisArgs, disposables);