diff --git a/app/client/components/CustomView.ts b/app/client/components/CustomView.ts
index 36a08157..2085a6a7 100644
--- a/app/client/components/CustomView.ts
+++ b/app/client/components/CustomView.ts
@@ -73,7 +73,7 @@ export class CustomView extends Disposable {
   private _emptyWidgetPage: string;
 
   public create(gristDoc: GristDoc, viewSectionModel: ViewSectionRec) {
-    BaseView.call(this as any, gristDoc, viewSectionModel);
+    BaseView.call(this as any, gristDoc, viewSectionModel, { 'addNewRow': true });
 
     this._customDef =  this.viewSection.customDef;
 
diff --git a/app/client/components/WidgetFrame.ts b/app/client/components/WidgetFrame.ts
index a2af7d0a..b214e45f 100644
--- a/app/client/components/WidgetFrame.ts
+++ b/app/client/components/WidgetFrame.ts
@@ -328,7 +328,7 @@ export class GristViewImpl implements GristView {
     // Hidden/Visible columns will eventually reflect what is available, but this operation
     // is not instant - and widget can receive rows with fields that are not in the mapping.
     const columns: ColumnRec[] = this._visibleColumns();
-    const rowIds: number[] = this._baseView.sortedRows.getKoArray().peek() as number[];
+    const rowIds = this._baseView.sortedRows.getKoArray().peek().filter(id => id != 'new');
     const data: BulkColValues = {};
     for (const column of columns) {
       // Use the colId of the displayCol, which may be different in case of Reference columns.
diff --git a/app/client/declarations.d.ts b/app/client/declarations.d.ts
index 5178d856..ac5b9b50 100644
--- a/app/client/declarations.d.ts
+++ b/app/client/declarations.d.ts
@@ -63,7 +63,7 @@ declare module "app/client/components/BaseView" {
     public isTruncated: ko.Observable<boolean>;
     public tableModel: DataTableModel;
 
-    constructor(gristDoc: GristDoc, viewSectionModel: any);
+    constructor(gristDoc: GristDoc, viewSectionModel: any, options?: {addNewRow?: boolean, isPreview?: boolean});
     public setCursorPos(cursorPos: CursorPos): void;
     public createFilterMenu(ctl: IOpenController, filterInfo: FilterInfo, onClose?: () => void): HTMLElement;
     public buildTitleControls(): DomArg;
diff --git a/app/plugin/grist-plugin-api.ts b/app/plugin/grist-plugin-api.ts
index c888a62a..dd17c180 100644
--- a/app/plugin/grist-plugin-api.ts
+++ b/app/plugin/grist-plugin-api.ts
@@ -310,12 +310,24 @@ export function mapColumnNamesBack(data: any, options: {
  */
 export function onRecord(callback: (data: RowRecord | null, mappings: WidgetColumnMap | null) => unknown) {
   on('message', async function(msg) {
-    if (!msg.tableId || !msg.rowId) { return; }
+    if (!msg.tableId || !msg.rowId || msg.rowId === 'new') { return; }
     const rec = await docApi.fetchSelectedRecord(msg.rowId);
     callback(rec, await getMappingsIfChanged(msg));
   });
 }
 
+/**
+ * For custom widgets, add a handler that will be called whenever the
+ * new (blank) row is selected.
+ */
+export function onNewRecord(callback: () => unknown) {
+  on('message', async function(msg) {
+    if (msg.tableId && msg.rowId === 'new') {
+      callback();
+    }
+  });
+}
+
 /**
  * For custom widgets, add a handler that will be called whenever the
  * selected records change.  Handler will be called with a list of records.