Show Bottom Sheet.

Samples/UIWidgetsGallery/gallery/demos.cs

                     documentationUrl: "https://docs.flutter.io/flutter/material/BottomNavigationBar-class.html",
                     buildRoute: (BuildContext context) => new BottomNavigationDemo()
                 ),
-//                new GalleryDemo(
-//                    title: "Bottom sheet: Modal",
-//                    subtitle: "A dismissable bottom sheet",
-//                    icon: GalleryIcons.bottom_sheets,
-//                    category: GalleryDemoCategory._kMaterialComponents,
-//                    routeName: ModalBottomSheetDemo.routeName,
-//                    documentationUrl: "https://docs.flutter.io/flutter/material/showModalBottomSheet.html",
-//                    buildRoute: (BuildContext context) => ModalBottomSheetDemo()
-//                ),
+                new GalleryDemo(
+                    title: "Bottom sheet: Modal",
+                    subtitle: "A dismissable bottom sheet",
+                    icon: GalleryIcons.bottom_sheets,
+                    category: _kMaterialComponents,
+                    routeName: ModalBottomSheetDemo.routeName,
+                    documentationUrl: "https://docs.flutter.io/flutter/material/showModalBottomSheet.html",
+                    buildRoute: (BuildContext context) => new ModalBottomSheetDemo()
+                ),
 //                new GalleryDemo(
 //                    title: "Bottom sheet: Persistent",
 //                    subtitle: "A bottom sheet that sticks around",

Samples/UIWidgetsGallery/demo/material/modal_bottom_sheet_demo.cs

+using System.Collections.Generic;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+
+namespace UIWidgetsGallery.gallery {
+    public class ModalBottomSheetDemo : StatelessWidget {
+        public const string routeName = "/material/modal-bottom-sheet";
+
+        public override Widget build(BuildContext context) {
+            return new Scaffold(
+                appBar: new AppBar(
+                    title: new Text("Modal bottom sheet"),
+                    actions: new List<Widget> {new MaterialDemoDocumentationButton(routeName)}
+                ),
+                body: new Center(
+                    child: new RaisedButton(
+                        child: new Text("SHOW BOTTOM SHEET"),
+                        onPressed: () => {
+                            BottomSheetUtils.showModalBottomSheet<object>(context: context,
+                                builder: (BuildContext _context) => {
+                                    return new Container(
+                                        child: new Padding(
+                                            padding: EdgeInsets.all(32.0f),
+                                            child: new Text("This is the modal bottom sheet. Tap anywhere to dismiss.",
+                                                textAlign: TextAlign.center,
+                                                style: new TextStyle(
+                                                    color: Theme.of(_context).accentColor,
+                                                    fontSize: 24.0f
+                                                )
+                                            )
+                                        )
+                                    );
+                                });
+                        }
+                    )
+                )
+            );
+        }
+    }
+}

Samples/UIWidgetsGallery/demo/material/modal_bottom_sheet_demo.cs.meta

+fileFormatVersion: 2
+guid: 3c47b9e1a46e47858145acbe84590d05
+timeCreated: 1555059325