diff --git a/app/client/components/CustomCalendarView.ts b/app/client/components/CustomCalendarView.ts
new file mode 100644
index 00000000..7777edcd
--- /dev/null
+++ b/app/client/components/CustomCalendarView.ts
@@ -0,0 +1,31 @@
+import {AccessLevel} from "app/common/CustomWidget";
+import {ViewSectionRec} from "app/client/models/entities/ViewSectionRec";
+import {CustomView} from "app/client/components/CustomView";
+import {GristDoc} from "app/client/components/GristDoc";
+
+//Abstract class for more future inheritances
+abstract class CustomAttachedView extends CustomView {
+  public override create(gristDoc: GristDoc, viewSectionModel: ViewSectionRec) {
+    super.create(gristDoc, viewSectionModel);
+    void viewSectionModel.customDef.access.setAndSave(AccessLevel.full);
+
+    const widgetsApi = this.gristDoc.app.topAppModel.api;
+    widgetsApi.getWidgets().then(async result=>{
+      const widget = result.find(w=>w.name == this.getWidgetName());
+      if(widget) {
+        await this.customDef.url.setAndSave(widget.url);
+      }
+    }).catch(()=>{
+      //do nothing
+    });
+  }
+
+  protected abstract getWidgetName(): string;
+
+}
+
+export class CustomCalendarView extends CustomAttachedView {
+  protected getWidgetName(): string {
+    return "Calendar";
+  }
+}
diff --git a/app/client/components/CustomView.ts b/app/client/components/CustomView.ts
index 71c51d56..439ff4fb 100644
--- a/app/client/components/CustomView.ts
+++ b/app/client/components/CustomView.ts
@@ -1,10 +1,18 @@
 import BaseView from 'app/client/components/BaseView';
-import {Cursor} from 'app/client/components/Cursor';
 import * as commands from 'app/client/components/commands';
+import {Cursor} from 'app/client/components/Cursor';
 import {GristDoc} from 'app/client/components/GristDoc';
-import {ConfigNotifier, CustomSectionAPIImpl, GristDocAPIImpl, GristViewImpl,
-        MinimumLevel, RecordNotifier, TableNotifier, WidgetAPIImpl,
-        WidgetFrame} from 'app/client/components/WidgetFrame';
+import {
+  ConfigNotifier,
+  CustomSectionAPIImpl,
+  GristDocAPIImpl,
+  GristViewImpl,
+  MinimumLevel,
+  RecordNotifier,
+  TableNotifier,
+  WidgetAPIImpl,
+  WidgetFrame
+} from 'app/client/components/WidgetFrame';
 import {CustomSectionElement, ViewProcess} from 'app/client/lib/CustomSectionElement';
 import {Disposable} from 'app/client/lib/dispose';
 import dom from 'app/client/lib/dom';
@@ -14,15 +22,16 @@ import {ViewSectionRec} from 'app/client/models/DocModel';
 import {CustomViewSectionDef} from 'app/client/models/entities/ViewSectionRec';
 import {UserError} from 'app/client/models/errors';
 import {SortedRowSet} from 'app/client/models/rowset';
-import {PluginInstance} from 'app/common/PluginInstance';
-import {AccessLevel} from 'app/common/CustomWidget';
 import {closeRegisteredMenu} from 'app/client/ui2018/menus';
+import {AccessLevel} from 'app/common/CustomWidget';
+import {PluginInstance} from 'app/common/PluginInstance';
 import {getGristConfig} from 'app/common/urlUtils';
 import {Events as BackboneEvents} from 'backbone';
 import {dom as grains} from 'grainjs';
 import * as ko from 'knockout';
 import defaults = require('lodash/defaults');
 
+
 /**
  * CustomView components displays arbitrary html. There are two modes available, in the "url" mode
  * the content is hosted by a third-party (for instance a github page), as opposed to the "plugin"
@@ -60,7 +69,7 @@ export class CustomView extends Disposable {
   protected gristDoc: GristDoc;
   protected cursor: Cursor;
 
-  private _customDef: CustomViewSectionDef;
+  protected customDef: CustomViewSectionDef;
 
   // state of the component
   private _foundPlugin: ko.Observable<boolean>;
@@ -70,14 +79,12 @@ export class CustomView extends Disposable {
   private _pluginInstance: PluginInstance|undefined;
 
   private _frame: WidgetFrame;  // plugin frame (holding external page)
-  private _emptyWidgetPage: string;
+
 
   public create(gristDoc: GristDoc, viewSectionModel: ViewSectionRec) {
     BaseView.call(this as any, gristDoc, viewSectionModel, { 'addNewRow': true });
 
-    this._customDef =  this.viewSection.customDef;
-
-    this._emptyWidgetPage = new URL("custom-widget.html", getGristConfig().homeUrl!).href;
+    this.customDef =  this.viewSection.customDef;
 
     this.autoDisposeCallback(() => {
       if (this._customSection) {
@@ -89,27 +96,31 @@ export class CustomView extends Disposable {
     // Ensure that selecting another section in same plugin update the view.
     this._foundSection.extend({notify: 'always'});
 
-    this.autoDispose(this._customDef.pluginId.subscribe(this._updatePluginInstance, this));
-    this.autoDispose(this._customDef.sectionId.subscribe(this._updateCustomSection, this));
+    this.autoDispose(this.customDef.pluginId.subscribe(this._updatePluginInstance, this));
+    this.autoDispose(this.customDef.sectionId.subscribe(this._updateCustomSection, this));
     this.autoDispose(commands.createGroup(CustomView._commands, this, this.viewSection.hasFocus));
 
     this.viewPane = this.autoDispose(this._buildDom());
     this._updatePluginInstance();
   }
 
+
   public async triggerPrint() {
     if (!this.isDisposed() && this._frame) {
       return await this._frame.callRemote('print');
     }
   }
 
+  protected getEmptyWidgetPage(): string {
+    return new URL("custom-widget.html", getGristConfig().homeUrl!).href;
+  }
   /**
    * Find a plugin instance that matches the plugin id, update the `found` observables, then tries to
    * find a matching section.
    */
   private _updatePluginInstance() {
 
-    const pluginId = this._customDef.pluginId();
+    const pluginId = this.customDef.pluginId();
     this._pluginInstance = this.gristDoc.docPluginManager.pluginsList.find(p => p.definition.id === pluginId);
 
     if (this._pluginInstance) {
@@ -129,7 +140,7 @@ export class CustomView extends Disposable {
 
     if (!this._pluginInstance) { return; }
 
-    const sectionId = this._customDef.sectionId();
+    const sectionId = this.customDef.sectionId();
     this._customSection = CustomSectionElement.find(this._pluginInstance, sectionId);
 
     if (this._customSection) {
@@ -142,8 +153,8 @@ export class CustomView extends Disposable {
   }
 
   private _buildDom() {
-    const {mode, url, access} = this._customDef;
-    const showPlugin = ko.pureComputed(() => this._customDef.mode() === "plugin");
+    const {mode, url, access} = this.customDef;
+    const showPlugin = ko.pureComputed(() => this.customDef.mode() === "plugin");
 
     // When both plugin and section are not found, let's show only plugin notification.
     const showPluginNotification = ko.pureComputed(() => showPlugin() && !this._foundPlugin());
@@ -161,12 +172,12 @@ export class CustomView extends Disposable {
       kd.scope(() => [mode(), url(), access()], ([_mode, _url, _access]: string[]) =>
         _mode === "url" ? this._buildIFrame(_url, (_access || AccessLevel.none) as AccessLevel) : null),
       kd.maybe(showPluginNotification, () => buildNotification('Plugin ',
-        dom('strong', kd.text(this._customDef.pluginId)), ' was not found',
+        dom('strong', kd.text(this.customDef.pluginId)), ' was not found',
         dom.testId('customView_notification_plugin')
       )),
       kd.maybe(showSectionNotification, () => buildNotification('Section ',
-        dom('strong', kd.text(this._customDef.sectionId)), ' was not found in plugin ',
-        dom('strong', kd.text(this._customDef.pluginId)),
+        dom('strong', kd.text(this.customDef.sectionId)), ' was not found in plugin ',
+        dom('strong', kd.text(this.customDef.pluginId)),
         dom.testId('customView_notification_section')
       )),
       // When showPluginContent() is true then _foundSection() is also and _customSection is not
@@ -184,7 +195,7 @@ export class CustomView extends Disposable {
 
   private _buildIFrame(baseUrl: string, access: AccessLevel) {
     return grains.create(WidgetFrame, {
-      url: baseUrl || this._emptyWidgetPage,
+      url: baseUrl || this.getEmptyWidgetPage(),
       access,
       readonly: this.gristDoc.isReadonly.get(),
       configure: (frame) => {
diff --git a/app/client/components/GristDoc.ts b/app/client/components/GristDoc.ts
index 610ef14f..d46ae3ce 100644
--- a/app/client/components/GristDoc.ts
+++ b/app/client/components/GristDoc.ts
@@ -47,7 +47,7 @@ import {IPageWidget, toPageWidget} from 'app/client/ui/PageWidgetPicker';
 import {linkFromId, selectBy} from 'app/client/ui/selectBy';
 import {WebhookPage} from 'app/client/ui/WebhookPage';
 import {startWelcomeTour} from 'app/client/ui/WelcomeTour';
-import {IWidgetType} from 'app/client/ui/widgetTypes';
+import {IWidgetType} from 'app/common/widgetTypes';
 import {PlayerState, YouTubePlayer} from 'app/client/ui/YouTubePlayer';
 import {isNarrowScreen, mediaSmall, mediaXSmall, testId, theme} from 'app/client/ui2018/cssVars';
 import {IconName} from 'app/client/ui2018/IconList';
diff --git a/app/client/components/ViewLayout.ts b/app/client/components/ViewLayout.ts
index e2c322e9..a7340c3e 100644
--- a/app/client/components/ViewLayout.ts
+++ b/app/client/components/ViewLayout.ts
@@ -1,12 +1,15 @@
 import BaseView from 'app/client/components/BaseView';
+import {buildViewSectionDom} from 'app/client/components/buildViewSectionDom';
 import {ChartView} from 'app/client/components/ChartView';
 import * as commands from 'app/client/components/commands';
+import {CustomCalendarView} from "app/client/components/CustomCalendarView";
 import {CustomView} from 'app/client/components/CustomView';
 import * as DetailView from 'app/client/components/DetailView';
 import * as GridView from 'app/client/components/GridView';
 import {GristDoc} from 'app/client/components/GristDoc';
 import {BoxSpec, Layout} from 'app/client/components/Layout';
 import {LayoutEditor} from 'app/client/components/LayoutEditor';
+import {LayoutTray} from 'app/client/components/LayoutTray';
 import {printViewSection} from 'app/client/components/Printing';
 import {Delay} from 'app/client/lib/Delay';
 import {createObsArray} from 'app/client/lib/koArrayWrap';
@@ -15,14 +18,23 @@ import {reportError} from 'app/client/models/errors';
 import {isNarrowScreen, mediaSmall, testId, theme} from 'app/client/ui2018/cssVars';
 import {icon} from 'app/client/ui2018/icons';
 import {DisposableWithEvents} from 'app/common/DisposableWithEvents';
-import {LayoutTray} from 'app/client/components/LayoutTray';
-import {buildViewSectionDom} from 'app/client/components/buildViewSectionDom';
 import {mod} from 'app/common/gutil';
+import {
+  Computed,
+  computedArray,
+  Disposable,
+  dom,
+  fromKo,
+  Holder,
+  IDomComponent,
+  MultiHolder,
+  Observable,
+  styled,
+  subscribe
+} from 'grainjs';
 import * as ko from 'knockout';
-import * as _ from 'underscore';
 import debounce from 'lodash/debounce';
-import {Computed, computedArray, Disposable, dom, fromKo, Holder,
-        IDomComponent, MultiHolder, Observable, styled, subscribe} from 'grainjs';
+import * as _ from 'underscore';
 
 // tslint:disable:no-console
 
@@ -32,6 +44,7 @@ const viewSectionTypes: {[key: string]: any} = {
   chart: ChartView,
   single: DetailView,
   custom: CustomView,
+  'custom.calendar': CustomCalendarView,
 };
 
 function getInstanceConstructor(parentKey: string) {
diff --git a/app/client/components/WidgetFrame.ts b/app/client/components/WidgetFrame.ts
index 645590ee..f4b5b40f 100644
--- a/app/client/components/WidgetFrame.ts
+++ b/app/client/components/WidgetFrame.ts
@@ -89,7 +89,6 @@ export class WidgetFrame extends DisposableWithEvents {
     // Call custom configuration handler.
     _options.configure?.(this);
   }
-
   /**
    * Attach an EventSource with desired access level.
    */
diff --git a/app/client/components/buildViewSectionDom.ts b/app/client/components/buildViewSectionDom.ts
index fc57b8bd..0715638f 100644
--- a/app/client/components/buildViewSectionDom.ts
+++ b/app/client/components/buildViewSectionDom.ts
@@ -1,16 +1,16 @@
 import BaseView from 'app/client/components/BaseView';
 import {GristDoc} from 'app/client/components/GristDoc';
-import {ViewRec, ViewSectionRec} from 'app/client/models/DocModel';
 import {makeT} from 'app/client/lib/localization';
+import {ViewRec, ViewSectionRec} from 'app/client/models/DocModel';
 import {filterBar} from 'app/client/ui/FilterBar';
 import {cssIcon} from 'app/client/ui/RightPanelStyles';
 import {makeCollapsedLayoutMenu} from 'app/client/ui/ViewLayoutMenu';
 import {cssDotsIconWrapper, cssMenu, viewSectionMenu} from 'app/client/ui/ViewSectionMenu';
 import {buildWidgetTitle} from 'app/client/ui/WidgetTitle';
-import {getWidgetTypes} from 'app/client/ui/widgetTypes';
 import {colors, isNarrowScreenObs, mediaSmall, testId, theme} from 'app/client/ui2018/cssVars';
 import {icon} from 'app/client/ui2018/icons';
 import {menu} from 'app/client/ui2018/menus';
+import {getWidgetTypes} from "app/client/ui/widgetTypesMap";
 import {Computed, dom, DomElementArg, Observable, styled} from 'grainjs';
 import {defaultMenuOptions} from 'popweasel';
 
diff --git a/app/client/models/entities/ViewSectionRec.ts b/app/client/models/entities/ViewSectionRec.ts
index d43123bd..f02c0c6b 100644
--- a/app/client/models/entities/ViewSectionRec.ts
+++ b/app/client/models/entities/ViewSectionRec.ts
@@ -1,6 +1,7 @@
 import BaseView from 'app/client/components/BaseView';
 import {LinkingState} from 'app/client/components/LinkingState';
 import {KoArray} from 'app/client/lib/koArray';
+import {ColumnToMapImpl} from 'app/client/models/ColumnToMap';
 import {
   ColumnRec,
   DocModel,
@@ -13,18 +14,17 @@ import {
   ViewFieldRec,
   ViewRec
 } from 'app/client/models/DocModel';
+import {BEHAVIOR} from 'app/client/models/entities/ColumnRec';
 import * as modelUtil from 'app/client/models/modelUtil';
+import {removeRule, RuleOwner} from 'app/client/models/RuleOwner';
 import {LinkConfig} from 'app/client/ui/selectBy';
-import {getWidgetTypes} from 'app/client/ui/widgetTypes';
+import {getWidgetTypes} from "app/client/ui/widgetTypesMap";
 import {FilterColValues} from "app/common/ActiveDocAPI";
 import {AccessLevel, ICustomWidget} from 'app/common/CustomWidget';
 import {UserAction} from 'app/common/DocActions';
 import {arrayRepeat} from 'app/common/gutil';
 import {Sort} from 'app/common/SortSpec';
 import {ColumnsToMap, WidgetColumnMap} from 'app/plugin/CustomSectionAPI';
-import {ColumnToMapImpl} from 'app/client/models/ColumnToMap';
-import {BEHAVIOR} from 'app/client/models/entities/ColumnRec';
-import {removeRule, RuleOwner} from 'app/client/models/RuleOwner';
 import {CursorPos, UIRowId} from 'app/plugin/GristAPI';
 import {Computed, Holder, Observable} from 'grainjs';
 import * as ko from 'knockout';
diff --git a/app/client/models/features.ts b/app/client/models/features.ts
index d19a8d28..353fe0a3 100644
--- a/app/client/models/features.ts
+++ b/app/client/models/features.ts
@@ -1,6 +1,6 @@
 import {getGristConfig} from 'app/common/urlUtils';
 import {get as getBrowserGlobals} from 'app/client/lib/browserGlobals';
-import {localStorageBoolObs} from 'app/client/lib/localStorageObs';
+import {localStorageBoolObs, localStorageJsonObs} from 'app/client/lib/localStorageObs';
 import {Observable} from 'grainjs';
 
 /**
@@ -24,3 +24,12 @@ export function HAS_FORMULA_ASSISTANT() {
 export function WHICH_FORMULA_ASSISTANT() {
   return getGristConfig().assistantService;
 }
+
+export function PERMITTED_CUSTOM_WIDGETS(): Observable<string[]> {
+  const G = getBrowserGlobals('document', 'window');
+  if (!G.window.PERMITTED_CUSTOM_WIDGETS) {
+    G.window.PERMITTED_CUSTOM_WIDGETS =
+      localStorageJsonObs('PERMITTED_CUSTOM_WIDGETS', getGristConfig().permittedCustomWidgets || []);
+  }
+  return G.window.PERMITTED_CUSTOM_WIDGETS;
+}
diff --git a/app/client/ui/CustomSectionConfig.ts b/app/client/ui/CustomSectionConfig.ts
index efa48232..4192c60d 100644
--- a/app/client/ui/CustomSectionConfig.ts
+++ b/app/client/ui/CustomSectionConfig.ts
@@ -1,6 +1,7 @@
 import {allCommands} from 'app/client/components/commands';
 import {GristDoc} from 'app/client/components/GristDoc';
 import * as kf from 'app/client/lib/koForm';
+import {makeT} from 'app/client/lib/localization';
 import {ColumnToMapImpl} from 'app/client/models/ColumnToMap';
 import {ColumnRec, ViewSectionRec} from 'app/client/models/DocModel';
 import {reportError} from 'app/client/models/errors';
@@ -16,10 +17,19 @@ import {cssLink} from 'app/client/ui2018/links';
 import {IOptionFull, menu, menuItem, menuText, select} from 'app/client/ui2018/menus';
 import {AccessLevel, ICustomWidget, isSatisfied} from 'app/common/CustomWidget';
 import {GristLoadConfig} from 'app/common/gristUrls';
-import {nativeCompare, unwrap} from 'app/common/gutil';
-import {bundleChanges, Computed, Disposable, dom, fromKo, makeTestId,
-        MultiHolder, Observable, styled, UseCBOwner} from 'grainjs';
-import {makeT} from 'app/client/lib/localization';
+import {unwrap} from 'app/common/gutil';
+import {
+  bundleChanges,
+  Computed,
+  Disposable,
+  dom,
+  fromKo,
+  makeTestId,
+  MultiHolder,
+  Observable,
+  styled,
+  UseCBOwner
+} from 'grainjs';
 
 const t = makeT('CustomSectionConfig');
 
@@ -165,8 +175,7 @@ class ColumnListPicker extends Disposable {
     const columns = use(this._section.columns).filter(this._typeFilter(use));
     const columnMap = new Map(columns.map(c => [c.id.peek(), c]));
     // Remove any columns that are no longer there.
-    const selectedFields = selectedRefs.map(s => columnMap.get(s)!).filter(c => Boolean(c));
-    return selectedFields;
+    return selectedRefs.map(s => columnMap.get(s)!).filter(c => Boolean(c));
   }
   private _renderItem(use: UseCBOwner, field: ColumnRec): any {
     return cssFieldEntry(
@@ -221,27 +230,82 @@ class ColumnListPicker extends Disposable {
   }
 }
 
+class CustomSectionConfigurationConfig extends Disposable{
+  // Does widget has custom configuration.
+  private readonly _hasConfiguration: Computed<boolean>;
+  constructor(private _section: ViewSectionRec) {
+    super();
+    this._hasConfiguration = Computed.create(this, use => use(_section.hasCustomOptions));
+  }
+  public buildDom() {
+    // Show prompt, when desired access level is different from actual one.
+    return dom(
+      'div',
+      dom.maybe(this._hasConfiguration, () =>
+        cssSection(
+          textButton(
+            t("Open configuration"),
+            dom.on('click', () => this._openConfiguration()),
+            testId('open-configuration')
+          )
+        )
+      ),
+      dom.maybeOwned(use => use(this._section.columnsToMap), (owner, columns) => {
+        const createObs = (column: ColumnToMapImpl) => {
+          const obs = Computed.create(owner, use => {
+            const savedDefinition = use(this._section.customDef.columnsMapping) || {};
+            return savedDefinition[column.name];
+          });
+          obs.onWrite(async (value) => {
+            const savedDefinition = this._section.customDef.columnsMapping.peek() || {};
+            savedDefinition[column.name] = value;
+            await this._section.customDef.columnsMapping.setAndSave(savedDefinition);
+          });
+          return obs;
+        };
+        // Create observables for all columns to pick.
+        const mappings = columns.map(c => new ColumnToMapImpl(c)).map((column) => ({
+          value: createObs(column),
+          column
+        }));
+        return [
+          ...mappings.map(m => m.column.allowMultiple
+            ? dom.create(ColumnListPicker, m.value, m.column, this._section)
+            : dom.create(ColumnPicker, m.value, m.column, this._section))
+        ];
+      })
+    );
+  }
+  private _openConfiguration(): void {
+    allCommands.openWidgetConfiguration.run();
+  }
+
+
+}
+
 export class CustomSectionConfig extends Disposable {
+
+  protected _customSectionConfigurationConfig: CustomSectionConfigurationConfig;
   // Holds all available widget definitions.
   private _widgets: Observable<ICustomWidget[]>;
   // Holds selected option (either custom string or a widgetId).
-  private _selectedId: Computed<string | null>;
+  private readonly _selectedId: Computed<string | null>;
   // Holds custom widget URL.
-  private _url: Computed<string>;
+  private readonly _url: Computed<string>;
   // Enable or disable widget repository.
-  private _canSelect = true;
+  private readonly _canSelect: boolean = true;
   // When widget is changed, it sets its desired access level. We will prompt
   // user to approve or reject it.
-  private _desiredAccess: Observable<AccessLevel|null>;
+  private readonly _desiredAccess: Observable<AccessLevel|null>;
   // Current access level (stored inside a section).
-  private _currentAccess: Computed<AccessLevel>;
-  // Does widget has custom configuration.
-  private _hasConfiguration: Computed<boolean>;
+  private readonly _currentAccess: Computed<AccessLevel>;
 
-  constructor(private _section: ViewSectionRec, private _gristDoc: GristDoc) {
+
+
+
+  constructor(protected _section: ViewSectionRec, private _gristDoc: GristDoc) {
     super();
-
-    const api = _gristDoc.app.topAppModel.api;
+    this._customSectionConfigurationConfig = new CustomSectionConfigurationConfig(_section);
 
     // Test if we can offer widget list.
     const gristConfig: GristLoadConfig = (window as any).gristConfig || {};
@@ -249,29 +313,8 @@ export class CustomSectionConfig extends Disposable {
 
     // Array of available widgets - will be updated asynchronously.
     this._widgets = Observable.create(this, []);
-
-    if (this._canSelect) {
-      // From the start we will provide single widget definition
-      // that was chosen previously.
-      if (_section.customDef.widgetDef.peek()) {
-        this._widgets.set([_section.customDef.widgetDef.peek()!]);
-      }
-      // Request for rest of the widgets.
-      api
-        .getWidgets()
-        .then(widgets => {
-          if (this.isDisposed()) {
-            return;
-          }
-          const existing = _section.customDef.widgetDef.peek();
-          // Make sure we have current widget in place.
-          if (existing && !widgets.some(w => w.widgetId === existing.widgetId)) {
-            widgets.push(existing);
-          }
-          this._widgets.set(widgets.sort((a, b) => nativeCompare(a.name.toLowerCase(), b.name.toLowerCase())));
-        })
-        .catch(reportError);
-    }
+    this._getWidgets().catch(reportError);
+    // Request for rest of the widgets.
 
     // Selected value from the dropdown (contains widgetId or "custom" string for Custom URL)
     this._selectedId = Computed.create(this, use => {
@@ -350,8 +393,6 @@ export class CustomSectionConfig extends Disposable {
 
     // Clear intermediate state when section changes.
     this.autoDispose(_section.id.subscribe(() => this._reject()));
-
-    this._hasConfiguration = Computed.create(this, use => use(_section.hasCustomOptions));
   }
 
   public buildDom() {
@@ -395,16 +436,17 @@ export class CustomSectionConfig extends Disposable {
     return dom(
       'div',
       dom.autoDispose(holder),
+      this.shouldRenderWidgetSelector() &&
       this._canSelect
         ? cssRow(
-            select(this._selectedId, options, {
-              defaultLabel: t("Select Custom Widget"),
-              menuCssClass: cssMenu.className,
-            }),
-            testId('select')
-          )
+          select(this._selectedId, options, {
+            defaultLabel: t("Select Custom Widget"),
+            menuCssClass: cssMenu.className,
+          }),
+          testId('select')
+        )
         : null,
-      dom.maybe(isCustom, () => [
+      dom.maybe(isCustom && this.shouldRenderWidgetSelector(), () => [
         cssRow(
           cssTextInput(
             this._url,
@@ -452,15 +494,6 @@ export class CustomSectionConfig extends Disposable {
           cssRow(select(this._currentAccess, levels), testId('access')),
         ]
       ),
-      dom.maybe(this._hasConfiguration, () =>
-        cssSection(
-          textButton(
-            t("Open configuration"),
-            dom.on('click', () => this._openConfiguration()),
-            testId('open-configuration')
-          )
-        )
-      ),
       cssSection(
         cssLink(
           dom.attr('href', 'https://support.getgrist.com/widget-custom'),
@@ -468,38 +501,38 @@ export class CustomSectionConfig extends Disposable {
           t("Learn more about custom widgets")
         )
       ),
-      dom.maybeOwned(use => use(this._section.columnsToMap), (owner, columns) => {
-        const createObs = (column: ColumnToMapImpl) => {
-          const obs = Computed.create(owner, use => {
-            const savedDefinition = use(this._section.customDef.columnsMapping) || {};
-            return savedDefinition[column.name];
-          });
-          obs.onWrite(async (value) => {
-            const savedDefinition = this._section.customDef.columnsMapping.peek() || {};
-            savedDefinition[column.name] = value;
-            await this._section.customDef.columnsMapping.setAndSave(savedDefinition);
-          });
-          return obs;
-        };
-        // Create observables for all columns to pick.
-        const mappings = columns.map(c => new ColumnToMapImpl(c)).map((column) => ({
-          value: createObs(column),
-          column
-        }));
-        return [
-          cssSeparator(),
-          ...mappings.map(m => m.column.allowMultiple
-            ? dom.create(ColumnListPicker, m.value, m.column, this._section)
-            : dom.create(ColumnPicker, m.value, m.column, this._section))
-        ];
-      })
+      cssSeparator(),
+      this._customSectionConfigurationConfig.buildDom(),
+      cssSection(
+        cssLink(
+          dom.attr('href', 'https://support.getgrist.com/widget-custom'),
+          dom.attr('target', '_blank'),
+          t("Learn more about custom widgets")
+        )
+      ),
     );
   }
 
-  private _openConfiguration(): void {
-    allCommands.openWidgetConfiguration.run();
+  protected shouldRenderWidgetSelector(): boolean {
+    return true;
   }
 
+  protected async _getWidgets() {
+    const api = this._gristDoc.app.topAppModel.api;
+    const wigets = await api.getWidgets();
+    // Request for rest of the widgets.
+    if (this._canSelect) {
+      // From the start we will provide single widget definition
+      // that was chosen previously.
+      if (this._section.customDef.widgetDef.peek()) {
+        wigets.push(this._section.customDef.widgetDef.peek()!);
+      }
+    }
+    this._widgets.set(wigets);
+  }
+
+
+
   private _accept() {
     if (this._desiredAccess.get()) {
       this._currentAccess.set(this._desiredAccess.get()!);
@@ -512,7 +545,6 @@ export class CustomSectionConfig extends Disposable {
   }
 }
 
-
 const cssWarningWrapper = styled('div', `
   padding-left: 8px;
   padding-top: 6px;
diff --git a/app/client/ui/PageWidgetPicker.ts b/app/client/ui/PageWidgetPicker.ts
index 81ce82fe..7fb23733 100644
--- a/app/client/ui/PageWidgetPicker.ts
+++ b/app/client/ui/PageWidgetPicker.ts
@@ -1,23 +1,37 @@
-import { BehavioralPromptsManager } from 'app/client/components/BehavioralPromptsManager';
-import { GristDoc } from 'app/client/components/GristDoc';
-import { makeT } from 'app/client/lib/localization';
-import { reportError } from 'app/client/models/AppModel';
-import { ColumnRec, TableRec, ViewSectionRec } from 'app/client/models/DocModel';
-import { GristTooltips } from 'app/client/ui/GristTooltips';
-import { linkId, NoLink } from 'app/client/ui/selectBy';
-import { withInfoTooltip } from 'app/client/ui/tooltips';
-import { getWidgetTypes, IWidgetType } from 'app/client/ui/widgetTypes';
-import { bigPrimaryButton } from "app/client/ui2018/buttons";
-import { overflowTooltip } from "app/client/ui/tooltips";
-import { theme, vars } from "app/client/ui2018/cssVars";
-import { icon } from "app/client/ui2018/icons";
-import { spinnerModal } from 'app/client/ui2018/modals';
-import { isLongerThan, nativeCompare } from "app/common/gutil";
-import { computed, Computed, Disposable, dom, domComputed, DomElementArg, fromKo, IOption, select} from "grainjs";
-import { makeTestId, Observable, onKeyDown, styled} from "grainjs";
-import without = require('lodash/without');
+import {BehavioralPromptsManager} from 'app/client/components/BehavioralPromptsManager';
+import {GristDoc} from 'app/client/components/GristDoc';
+import {makeT} from 'app/client/lib/localization';
+import {reportError} from 'app/client/models/AppModel';
+import {ColumnRec, TableRec, ViewSectionRec} from 'app/client/models/DocModel';
+import {PERMITTED_CUSTOM_WIDGETS} from "app/client/models/features";
+import {GristTooltips} from 'app/client/ui/GristTooltips';
+import {linkId, NoLink} from 'app/client/ui/selectBy';
+import {overflowTooltip, withInfoTooltip} from 'app/client/ui/tooltips';
+import {getWidgetTypes} from "app/client/ui/widgetTypesMap";
+import {bigPrimaryButton} from "app/client/ui2018/buttons";
+import {theme, vars} from "app/client/ui2018/cssVars";
+import {icon} from "app/client/ui2018/icons";
+import {spinnerModal} from 'app/client/ui2018/modals';
+import {isLongerThan, nativeCompare} from "app/common/gutil";
+import {IAttachedCustomWidget, IWidgetType} from 'app/common/widgetTypes';
+import {
+  computed,
+  Computed,
+  Disposable,
+  dom,
+  domComputed,
+  DomElementArg,
+  fromKo,
+  IOption,
+  makeTestId,
+  Observable,
+  onKeyDown,
+  select,
+  styled
+} from "grainjs";
 import Popper from 'popper.js';
-import { IOpenController, popupOpen, setPopupToCreateDom } from 'popweasel';
+import {IOpenController, popupOpen, setPopupToCreateDom} from 'popweasel';
+import without = require('lodash/without');
 
 const t = makeT('PageWidgetPicker');
 
@@ -79,7 +93,7 @@ const testId = makeTestId('test-wselect-');
 // compatible types given the tableId and whether user is creating a new page or not.
 function getCompatibleTypes(tableId: TableId, isNewPage: boolean|undefined): IWidgetType[] {
   if (tableId !== 'New Table') {
-    return ['record', 'single', 'detail', 'chart', 'custom'];
+    return ['record', 'single', 'detail', 'chart', 'custom', 'custom.calendar'];
   } else if (isNewPage) {
     // New view + new table means we'll be switching to the primary view.
     return ['record'];
@@ -240,9 +254,15 @@ export interface ISelectOptions {
   selectBy?: (val: IPageWidget) => Array<IOption<string>>;
 }
 
+const registeredCustomWidgets: IAttachedCustomWidget[] =  ['custom.calendar'];
+
+const permittedCustomWidgets: IAttachedCustomWidget[] = PERMITTED_CUSTOM_WIDGETS().get().map((widget) =>
+  widget as IAttachedCustomWidget)??[];
 // the list of widget types in the order they should be listed by the widget.
+const finalListOfCustomWidgetToShow =  permittedCustomWidgets.filter(a=>
+  registeredCustomWidgets.includes(a));
 const sectionTypes: IWidgetType[] = [
-  'record', 'single', 'detail', 'chart', 'custom'
+  'record', 'single', 'detail', 'chart', ...finalListOfCustomWidgetToShow, 'custom'
 ];
 
 
diff --git a/app/client/ui/PredefinedCustomSectionConfig.ts b/app/client/ui/PredefinedCustomSectionConfig.ts
new file mode 100644
index 00000000..b31bbdc4
--- /dev/null
+++ b/app/client/ui/PredefinedCustomSectionConfig.ts
@@ -0,0 +1,23 @@
+import {GristDoc} from "../components/GristDoc";
+import {ViewSectionRec} from "../models/entities/ViewSectionRec";
+import {CustomSectionConfig} from "./CustomSectionConfig";
+
+export class PredefinedCustomSectionConfig extends CustomSectionConfig {
+
+
+  constructor(section: ViewSectionRec, gristDoc: GristDoc) {
+    super(section, gristDoc);
+  }
+
+  public buildDom() {
+    return this._customSectionConfigurationConfig.buildDom();
+  }
+
+  protected shouldRenderWidgetSelector(): boolean {
+    return false;
+  }
+
+  protected async _getWidgets(): Promise<void> {
+    // Do nothing.
+  }
+}
diff --git a/app/client/ui/RightPanel.ts b/app/client/ui/RightPanel.ts
index 2cbbc2f7..a9e21037 100644
--- a/app/client/ui/RightPanel.ts
+++ b/app/client/ui/RightPanel.ts
@@ -24,15 +24,16 @@ import {makeT} from 'app/client/lib/localization';
 import {createSessionObs} from 'app/client/lib/sessionObs';
 import {reportError} from 'app/client/models/AppModel';
 import {ViewSectionRec} from 'app/client/models/DocModel';
-import {GridOptions} from 'app/client/ui/GridOptions';
-import {attachPageWidgetPicker, IPageWidget, toPageWidget} from 'app/client/ui/PageWidgetPicker';
-import {linkId, selectBy} from 'app/client/ui/selectBy';
 import {CustomSectionConfig} from 'app/client/ui/CustomSectionConfig';
 import {buildDescriptionConfig} from 'app/client/ui/DescriptionConfig';
 import {BuildEditorOptions} from 'app/client/ui/FieldConfig';
+import {GridOptions} from 'app/client/ui/GridOptions';
+import {attachPageWidgetPicker, IPageWidget, toPageWidget} from 'app/client/ui/PageWidgetPicker';
+import {PredefinedCustomSectionConfig} from "app/client/ui/PredefinedCustomSectionConfig";
 import {cssLabel} from 'app/client/ui/RightPanelStyles';
+import {linkId, selectBy} from 'app/client/ui/selectBy';
 import {VisibleFieldsConfig} from 'app/client/ui/VisibleFieldsConfig';
-import {IWidgetType, widgetTypes} from 'app/client/ui/widgetTypes';
+import {widgetTypesMap} from "app/client/ui/widgetTypesMap";
 import {basicButton, primaryButton} from 'app/client/ui2018/buttons';
 import {testId, theme, vars} from 'app/client/ui2018/cssVars';
 import {textInput} from 'app/client/ui2018/editableLabel';
@@ -41,9 +42,22 @@ import {icon} from 'app/client/ui2018/icons';
 import {select} from 'app/client/ui2018/menus';
 import {FieldBuilder} from 'app/client/widgets/FieldBuilder';
 import {StringUnion} from 'app/common/StringUnion';
-import {bundleChanges, Computed, Disposable, dom, domComputed, DomContents,
-        DomElementArg, DomElementMethod, IDomComponent} from 'grainjs';
-import {MultiHolder, Observable, styled, subscribe} from 'grainjs';
+import {IWidgetType} from 'app/common/widgetTypes';
+import {
+  bundleChanges,
+  Computed,
+  Disposable,
+  dom,
+  domComputed,
+  DomContents,
+  DomElementArg,
+  DomElementMethod,
+  IDomComponent,
+  MultiHolder,
+  Observable,
+  styled,
+  subscribe
+} from 'grainjs';
 import * as ko from 'knockout';
 
 const t = makeT('RightPanel');
@@ -170,7 +184,7 @@ export class RightPanel extends Disposable {
 
   private _buildStandardHeader() {
     return dom.maybe(this._pageWidgetType, (type) => {
-      const widgetInfo = widgetTypes.get(type) || {label: 'Table', icon: 'TypeTable'};
+      const widgetInfo = widgetTypesMap.get(type) || {label: 'Table', icon: 'TypeTable'};
       const fieldInfo = getFieldType(type);
       return [
         cssTopBarItem(cssTopBarIcon(widgetInfo.icon), widgetInfo.label,
@@ -359,7 +373,8 @@ export class RightPanel extends Disposable {
     // refactored, but if not, should be made public.
     const viewConfigTab = this._createViewConfigTab(owner);
     const hasCustomMapping = Computed.create(owner, use => {
-      const isCustom = use(this._pageWidgetType) === 'custom';
+      const widgetType = use(this._pageWidgetType);
+      const isCustom = widgetType === 'custom' || widgetType?.startsWith('custom.');
       const hasColumnMapping = use(activeSection.columnsToMap);
       return Boolean(isCustom && hasColumnMapping);
     });
@@ -441,10 +456,15 @@ export class RightPanel extends Disposable {
             () => dom('div', parts[2].buildDom())),
           // In the default url mode, allow picking a url and granting/forbidding
           // access to data.
-          dom.maybe(use => use(activeSection.customDef.mode) === 'url',
+          dom.maybe(use => use(activeSection.customDef.mode) === 'url' && use(this._pageWidgetType) === 'custom',
             () => dom.create(CustomSectionConfig, activeSection, this._gristDoc)),
         ];
       }),
+      dom.maybe((use) =>  use(this._pageWidgetType)?.startsWith('custom.'), () => {
+        return [
+          dom.create(PredefinedCustomSectionConfig, activeSection, this._gristDoc),
+        ];
+      }),
 
       dom.maybe(
         (use) => !(
diff --git a/app/client/ui/VisibleFieldsConfig.ts b/app/client/ui/VisibleFieldsConfig.ts
index ba4224b1..01cae124 100644
--- a/app/client/ui/VisibleFieldsConfig.ts
+++ b/app/client/ui/VisibleFieldsConfig.ts
@@ -5,7 +5,7 @@ import { makeT } from 'app/client/lib/localization';
 import * as tableUtil from 'app/client/lib/tableUtil';
 import { ColumnRec, ViewFieldRec, ViewSectionRec } from "app/client/models/DocModel";
 import { getFieldType } from "app/client/ui/RightPanel";
-import { IWidgetType } from "app/client/ui/widgetTypes";
+import { IWidgetType } from "../../common/widgetTypes";
 import { basicButton, cssButton, primaryButton } from 'app/client/ui2018/buttons';
 import * as checkbox from "app/client/ui2018/checkbox";
 import { theme, vars } from "app/client/ui2018/cssVars";
diff --git a/app/client/ui/widgetTypes.ts b/app/client/ui/widgetTypes.ts
deleted file mode 100644
index b91a303d..00000000
--- a/app/client/ui/widgetTypes.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-/**
- * Exposes utilities for getting the types information associated to each of the widget types.
- */
-
-import { IconName } from "app/client/ui2018/IconList";
-
-// all widget types
-export type IWidgetType = 'record' | 'detail' | 'single' | 'chart' | 'custom';
-
-// Widget type info.
-export interface IWidgetTypeInfo {
-  label: string;
-  icon: IconName;
-}
-
-// the list of widget types with their labels and icons
-export const widgetTypes = new Map<IWidgetType, IWidgetTypeInfo> ([
-  ['record', {label: 'Table', icon: 'TypeTable'}],
-  ['single', {label: 'Card', icon: 'TypeCard'}],
-  ['detail', {label: 'Card List', icon: 'TypeCardList'}],
-  ['chart', {label: 'Chart', icon: 'TypeChart'}],
-  ['custom', {label: 'Custom', icon: 'TypeCustom'}]
-]);
-
-// Returns the widget type info for sectionType, or the one for 'record' if sectionType is null.
-export function getWidgetTypes(sectionType: IWidgetType|null): IWidgetTypeInfo {
-  return widgetTypes.get(sectionType || 'record') || widgetTypes.get('record')!;
-}
diff --git a/app/client/ui/widgetTypesMap.ts b/app/client/ui/widgetTypesMap.ts
new file mode 100644
index 00000000..9e2bc614
--- /dev/null
+++ b/app/client/ui/widgetTypesMap.ts
@@ -0,0 +1,23 @@
+// the list of widget types with their labels and icons
+import {IWidgetType} from "app/common/widgetTypes";
+import {IconName} from "app/client/ui2018/IconList";
+
+export const widgetTypesMap = new Map<IWidgetType, IWidgetTypeInfo>([
+  ['record', {label: 'Table', icon: 'TypeTable'}],
+  ['single', {label: 'Card', icon: 'TypeCard'}],
+  ['detail', {label: 'Card List', icon: 'TypeCardList'}],
+  ['chart', {label: 'Chart', icon: 'TypeChart'}],
+  ['custom', {label: 'Custom', icon: 'TypeCustom'}],
+  ['custom.calendar', {label: 'Calendar', icon: 'FieldDate'}]
+]);
+
+// Widget type info.
+export interface IWidgetTypeInfo {
+  label: string;
+  icon: IconName;
+}
+
+// Returns the widget type info for sectionType, or the one for 'record' if sectionType is null.
+export function getWidgetTypes(sectionType: IWidgetType | null): IWidgetTypeInfo {
+  return widgetTypesMap.get(sectionType || 'record') || widgetTypesMap.get('record')!;
+}
diff --git a/app/common/gristUrls.ts b/app/common/gristUrls.ts
index d4f06b6d..92c5f641 100644
--- a/app/common/gristUrls.ts
+++ b/app/common/gristUrls.ts
@@ -8,6 +8,8 @@ import {TelemetryLevel} from 'app/common/Telemetry';
 import {getGristConfig} from 'app/common/urlUtils';
 import {Document} from 'app/common/UserAPI';
 import {UIRowId} from 'app/plugin/GristAPI';
+import {IAttachedCustomWidget} from "app/common/widgetTypes";
+import {ThemeAppearance, ThemeAppearanceChecker, ThemeName, ThemeNameChecker} from './ThemePrefs';
 import clone = require('lodash/clone');
 import pickBy = require('lodash/pickBy');
 import {ThemeAppearance, ThemeAppearanceChecker, ThemeName, ThemeNameChecker} from './ThemePrefs';
@@ -666,6 +668,8 @@ export interface GristLoadConfig {
   // TODO: remove once released.
   featureFormulaAssistant?: boolean;
 
+  permittedCustomWidgets?: IAttachedCustomWidget[];
+
   // Used to determine which disclosure links should be provided to user of
   // formula assistance.
   assistantService?: 'OpenAI' | undefined;
diff --git a/app/common/widgetTypes.ts b/app/common/widgetTypes.ts
new file mode 100644
index 00000000..3b20ffbe
--- /dev/null
+++ b/app/common/widgetTypes.ts
@@ -0,0 +1,11 @@
+/**
+ * Exposes utilities for getting the types information associated to each of the widget types.
+ */
+import {StringUnion} from "app/common/StringUnion";
+
+// Custom widgets that are attached to "Add New" menu.
+export const AttachedCustomWidgets = StringUnion('custom.calendar');
+export type IAttachedCustomWidget = typeof AttachedCustomWidgets.type;
+
+// all widget types
+export type IWidgetType = 'record' | 'detail' | 'single' | 'chart' | 'custom' | IAttachedCustomWidget;
diff --git a/app/server/lib/sendAppPage.ts b/app/server/lib/sendAppPage.ts
index ca5b31ff..d80bc0d3 100644
--- a/app/server/lib/sendAppPage.ts
+++ b/app/server/lib/sendAppPage.ts
@@ -2,6 +2,7 @@ import {Features, getPageTitleSuffix, GristLoadConfig, IFeature} from 'app/commo
 import {isAffirmative} from 'app/common/gutil';
 import {getTagManagerSnippet} from 'app/common/tagManager';
 import {Document} from 'app/common/UserAPI';
+import {AttachedCustomWidgets, IAttachedCustomWidget} from "app/common/widgetTypes";
 import {SUPPORT_EMAIL} from 'app/gen-server/lib/HomeDBManager';
 import {isAnonymousUser, isSingleUserMode, RequestWithLogin} from 'app/server/lib/Authorizer';
 import {RequestWithOrg} from 'app/server/lib/extractOrg';
@@ -11,8 +12,8 @@ import {getSupportedEngineChoices} from 'app/server/lib/serverUtils';
 import {readLoadedLngs, readLoadedNamespaces} from 'app/server/localization';
 import * as express from 'express';
 import * as fse from 'fs-extra';
-import jsesc from 'jsesc';
 import * as handlebars from 'handlebars';
+import jsesc from 'jsesc';
 import * as path from 'path';
 import difference = require('lodash/difference');
 
@@ -76,6 +77,7 @@ export function makeGristConfig(options: MakeGristConfigOptons): GristLoadConfig
     featureComments: isAffirmative(process.env.COMMENTS),
     featureFormulaAssistant: Boolean(process.env.OPENAI_API_KEY || process.env.ASSISTANT_CHAT_COMPLETION_ENDPOINT),
     assistantService: process.env.OPENAI_API_KEY ? 'OpenAI' : undefined,
+    permittedCustomWidgets: getPermittedCustomWidgets(),
     supportEmail: SUPPORT_EMAIL,
     userLocale: (req as RequestWithLogin | undefined)?.user?.options?.locale,
     telemetry: server?.getTelemetry().getTelemetryConfig(),
@@ -166,6 +168,11 @@ function getFeatures(): IFeature[] {
   return Features.checkAll(difference(enabledFeatures, disabledFeatures));
 }
 
+function getPermittedCustomWidgets(): IAttachedCustomWidget[] {
+  const widgetsList = process.env.PERMITTED_CUSTOM_WIDGETS?.split(',').map(widgetName=>`custom.${widgetName}`) ?? [];
+  return  AttachedCustomWidgets.checkAll(widgetsList);
+}
+
 function configuredPageTitleSuffix() {
   const result = process.env.GRIST_PAGE_TITLE_SUFFIX;
   return result === "_blank" ? "" : result;
diff --git a/buildtools/fly-deploy.js b/buildtools/fly-deploy.js
index 24f2ab89..8df50687 100644
--- a/buildtools/fly-deploy.js
+++ b/buildtools/fly-deploy.js
@@ -67,7 +67,7 @@ const appExists = (name) => runFetch(`flyctl status -a ${name}`).then(() => true
 const appCreate = (name) => runAction(`flyctl launch --auto-confirm --name ${name} -r ewr -o ${org} --vm-memory 1024`);
 const volCreate = (name, vol) => runAction(`flyctl volumes create ${vol} -s 1 -r ewr -y -a ${name}`);
 const volList = (name) => runFetch(`flyctl volumes list -a ${name} -j`).then(({stdout}) => JSON.parse(stdout));
-const appDeploy = (name, appRoot) => runAction(`flyctl deploy ${appRoot} --remote-only`, {shell: true, stdio: 'inherit'});
+const appDeploy = (name, appRoot) => runAction(`flyctl deploy ${appRoot} --remote-only --region=ewr`, {shell: true, stdio: 'inherit'});
 
 async function appDestroy(name) {
   await runAction(`flyctl apps destroy ${name} -y`);
diff --git a/buildtools/fly-template.toml b/buildtools/fly-template.toml
index b6846e3f..2345f059 100644
--- a/buildtools/fly-template.toml
+++ b/buildtools/fly-template.toml
@@ -9,6 +9,7 @@ processes = []
   APP_HOME_URL="https://{APP_NAME}.fly.dev"
   APP_STATIC_URL="https://{APP_NAME}.fly.dev"
   ALLOWED_WEBHOOK_DOMAINS="webhook.site"
+  PERMITTED_CUSTOM_WIDGETS="calendar"
   GRIST_SINGLE_ORG="docs"
   PORT = "8080"
   FLY_DEPLOY_EXPIRATION = "{FLY_DEPLOY_EXPIRATION}"
diff --git a/test/nbrowser/CustomAttachedWidget.ts b/test/nbrowser/CustomAttachedWidget.ts
new file mode 100644
index 00000000..98043770
--- /dev/null
+++ b/test/nbrowser/CustomAttachedWidget.ts
@@ -0,0 +1,116 @@
+import {ICustomWidget} from "app/common/CustomWidget";
+import {getAppRoot} from "app/server/lib/places";
+import {assert, By, driver} from "mocha-webdriver";
+import path from "path";
+import * as gu from "test/nbrowser/gristUtils";
+import {server, setupTestSuite} from "test/nbrowser/testUtils";
+import {serveSomething} from "test/server/customUtil";
+import {EnvironmentSnapshot} from "test/server/testUtils";
+
+describe('attachedCustomWidget NotepadWidget', function () {
+  this.timeout(20000);
+  const cleanup = setupTestSuite();
+  let oldEnv: EnvironmentSnapshot;
+  // Valid manifest url.
+  const manifestEndpoint = '/manifest.json';
+  // Valid widget url.
+  const widgetEndpoint = '/widget';
+  // Create some widgets:
+  const widget1: ICustomWidget = {widgetId: '1', name: 'Calendar', url: widgetEndpoint + '?name=Calendar'};
+  let widgetServerUrl = '';
+  // Holds widgets manifest content.
+  let widgets: ICustomWidget[] = [];
+  // Switches widget manifest url
+  function useManifest(url: string) {
+    return server.testingHooks.setWidgetRepositoryUrl(url ? `${widgetServerUrl}${url}` : '');
+  }
+
+  async function buildWidgetServer(){
+    // Create simple widget server that serves manifest.json file, some widgets and some error pages.
+    const widgetServer = await serveSomething(app => {
+      app.get(widgetEndpoint, (req, res) =>
+        res
+          .header('Content-Type', 'text/html')
+          .send('<html><head><script src="/grist-plugin-api.js"></script></head><body>\n' +
+            (req.query.name || req.query.access) + // send back widget name from query string or access level
+            '</body>'+
+            "<script>grist.ready({requiredAccess: 'full', columns: [{name: 'Content', type: 'Text'}],"+
+            " onEditOptions(){}})</script>"+
+            '</html>\n')
+          .end()
+      );
+      app.get(manifestEndpoint, (_, res) =>
+        res
+          .header('Content-Type', 'application/json')
+          // prefix widget endpoint with server address
+          .json(widgets.map(widget => ({...widget, url: `${widgetServerUrl}${widget.url}`})))
+          .end()
+      );
+      app.get('/grist-plugin-api.js', (_, res) =>
+        res.sendFile(
+          'grist-plugin-api.js', {
+            root: path.resolve(getAppRoot(), "static")
+          }));
+    });
+
+    cleanup.addAfterAll(widgetServer.shutdown);
+    widgetServerUrl = widgetServer.url;
+
+    widgets = [widget1];
+  }
+
+  before(async function () {
+    await buildWidgetServer();
+    oldEnv = new EnvironmentSnapshot();
+    process.env.PERMITTED_CUSTOM_WIDGETS = "calendar";
+    await server.restart();
+    await useManifest(manifestEndpoint);
+    const session = await gu.session().login();
+    await session.tempDoc(cleanup, 'Hello.grist');
+
+  });
+
+  after(async function () {
+    oldEnv.restore();
+    await server.restart();
+  });
+
+  it('should be able to attach Calendar Widget', async () => {
+    await gu.openAddWidgetToPage();
+    const notepadElement = await driver.findContent('.test-wselect-type', /Calendar/);
+    assert.exists(notepadElement, 'Calendar widget is not found in the list of widgets');
+  });
+
+  it('should not ask for permission', async () => {
+    await gu.addNewSection(/Calendar/, /Table1/, {selectBy: /TABLE1/});
+    await gu.getSection('TABLE1 Calendar').click();
+    await gu.toggleSidePanel('right', 'open');
+    await driver.find('.test-right-tab-pagewidget').click();
+
+    await gu.waitForServer();
+
+    // Check if widget config panel is here
+    await driver.findWait('.test-config-container', 2000);
+
+    const widgetOptions = await driver.findWait('.test-config-widget-open-configuration', 2000);
+    const widgetMapping = await driver.find('.test-config-widget-mapping-for-Content');
+    const widgetSelection = await driver.findElements(By.css('.test-config-widget-select'));
+    const widgetPermission = await driver.findElements(By.css('.test-wselect-permission'));
+
+    assert.isEmpty(widgetSelection, 'Widget selection is not expected to be present');
+    assert.isEmpty(widgetPermission, 'Widget permission is not expected to be present');
+    assert.exists(widgetOptions, 'Widget options is expected to be present');
+    assert.exists(widgetMapping, 'Widget mapping is expected to be present');
+  });
+
+  it('should display the content of the widget', async () => {
+    await gu.getSection('TABLE1 Calendar').click();
+    try {
+      await driver.switchTo().frame(await driver.findWait('.custom_view', 1000));
+      const editor = await driver.findContentWait('body', "Calendar", 1000);
+      assert.exists(editor);
+    } finally {
+      await driver.switchTo().defaultContent();
+    }
+  });
+});