<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:ListViewRefresh"
             xmlns:telerikInput="clr-namespace:Telerik.XamarinForms.Input;assembly=Telerik.XamarinForms.Input"
             xmlns:telerikPrimitives="clr-namespace:Telerik.XamarinForms.Primitives;assembly=Telerik.XamarinForms.Primitives"
             x:Class="ListViewRefresh.MainPage">

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"></RowDefinition>
        </Grid.RowDefinitions>
        <Button HorizontalOptions="Center" Grid.Row="0"
        VerticalOptions="Start" 
        Text="Click here to rate" 
        Clicked="BtnTest_Clicked">
            <telerikPrimitives:RadPopup.Popup>
                <telerikPrimitives:RadPopup x:Name="popup"
                                    Placement="Bottom"
                                    OutsideBackgroundColor="#6F000000">
                    <telerikPrimitives:RadBorder CornerRadius="8" 
                                         WidthRequest="800" 
                                         HeightRequest="1000"
                                         Padding="10"
                                         VerticalOptions="FillAndExpand"
                                         BackgroundColor="Wheat">
                        <Grid Padding="20">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="30" />
                                <RowDefinition Height="20" />
                                <RowDefinition Height="40" />
                            </Grid.RowDefinitions>
                            <Label Text="Please rate your experience" />
                            <telerikInput:RadShapeRating Grid.Row="1" />
                            <Button Grid.Row="2"
                            Padding="2"
                            HorizontalOptions="End" 
                            Text="Send" 
                            Clicked="Button_Clicked" />
                        </Grid>
                    </telerikPrimitives:RadBorder>
                </telerikPrimitives:RadPopup>
            </telerikPrimitives:RadPopup.Popup>
        </Button>
    </Grid>

    
</ContentPage>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace ListViewRefresh
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void BtnTest_Clicked(object sender, EventArgs e)
        {
            popup.IsOpen = true;
        }

        private void Button_Clicked(object sender, EventArgs e)
        {
            popup.IsOpen = false;
        }
    }
}