<telerikDataControls:RadListView.LayoutDefinition>
       <telerikListView:ListViewLinearLayout ItemLength="400" />
</telerikDataControls:RadListView.LayoutDefinition>

    <ContentPage.Resources>
        <ResourceDictionary>
            <Style x:Key="PopupSpinnerStyle" TargetType="telerikDataControls:RadSpinner">
                <Setter Property="HeightRequest" Value="220" />
                <Setter Property="ItemLength" Value="44" />
                <Setter Property="Margin" Value="0, 16"/>
                <Setter Property="ItemStyle">
                    <Setter.Value>
                        <Style TargetType="telerikDataControls:SpinnerItemView">
                            <Setter Property="TextColor" Value="LightCoral" />
                        </Style>
                    </Setter.Value>
                </Setter>
                <Setter Property="SelectedItemStyle">
                    <Setter.Value>
                        <Style TargetType="telerikDataControls:SpinnerItemView">
                            <Setter Property="TextColor" Value="Black" />
                            <Setter Property="FontAttributes" Value="Bold" />
                        </Style>
                    </Setter.Value>
                </Setter>
            </Style>

        </ResourceDictionary>
    </ContentPage.Resources>
    <StackLayout>
        <telerikInput:RadTimePicker SpinnerStyle="{StaticResource PopupSpinnerStyle}"/>
    </StackLayout>

    <ContentPage.Resources>
        <ResourceDictionary>

            <telerikGrid:DataGridColumnHeaderStyle x:Key="headerstyle"
                                           TextColor="Black" OptionsButtonMargin="0,0,20,0" 
                                                   OptionsButtonFontSize="30"
                                           BorderColor="Black" 
                                           BorderThickness="2"/>
        </ResourceDictionary>
    </ContentPage.Resources>
    <Grid>
        <telerikGrid:RadDataGrid ItemsSource="{Binding Items}" BackgroundColor="Red" AutoGenerateColumns="false">
            <telerikGrid:RadDataGrid.Columns>
                <telerikGrid:DataGridTextColumn PropertyName="Country" HeaderStyle="{StaticResource headerstyle}"/>
                <telerikGrid:DataGridTextColumn PropertyName="Capital" HeaderStyle="{StaticResource headerstyle}"/>
            </telerikGrid:RadDataGrid.Columns>
        </telerikGrid:RadDataGrid>
    </Grid>

 var tabItem = new TabViewItem()
 {
     Header = new TabViewHeaderItem { Text = "Prague" },
     Content = new StackLayout
     {
         Children =
         {
             new Label {Text = "Prague"}
         }
     },
 };
 var index = tabView.Items.Count - 2;
 tabView.Items.Insert(index, tabItem);