Cancel automatic focus on entry using xamarin telerik popup - xamarin

Question

I'm using a Telerik RadPopup composed with an entry and checkbox's.
When I open the popup, the focus is directly is the entry. But I dont want a focus in any component.
It is possible using this type of popup ?
There is the code
<telerikPrimitives:RadPopup.Popup>
<telerikPrimitives:RadPopup Placement="Center" IsModal="False" OutsideBackgroundColor="#6F000000" IsOpen="{Binding WantSendEmail}">
<telerikPrimitives:RadBorder CornerRadius="8" BackgroundColor="{StaticResource Key=LightBackgroundColor}">
<Frame HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Padding="0" Margin="0" WidthRequest="250">
<StackLayout Orientation="Vertical" >
<StackLayout BackgroundColor="{StaticResource Key=MainButtonPrimaryColor}"
HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<Label Text="Envoi par Email" HorizontalOptions="CenterAndExpand" FontSize="{Binding FontSizeXSmall}"
Padding="10"
TextColor="White" VerticalOptions="CenterAndExpand"/>
</StackLayout>
<StackLayout Orientation="Horizontal" Padding="10,10,10,0"
HorizontalOptions="StartAndExpand" VerticalOptions="CenterAndExpand">
<CheckBox IsChecked="{Binding SaisieLibre, Converter={StaticResource cnvInverseBoolConverter}}" Color="{StaticResource Key=MainButtonPrimaryColor}"/>
<ContentView Focused="ContentView_Focused" Content="{Binding EntrySearchTiers}" Padding="10,10,10,0"
IsEnabled="{Binding SaisieLibre, Converter={StaticResource cnvInverseBoolConverter}}"/>
</StackLayout>
<StackLayout Orientation="Horizontal" Padding="10,10,10,0"
HorizontalOptions="StartAndExpand" VerticalOptions="CenterAndExpand">
<CheckBox IsChecked="{Binding SaisieLibre}" Color="{StaticResource Key=MainButtonPrimaryColor}"/>
<Label Text="Saisie Libre" VerticalOptions="CenterAndExpand"/>
</StackLayout>
<StackLayout Orientation="Horizontal" Padding="10,10,10,0"
HorizontalOptions="StartAndExpand" VerticalOptions="CenterAndExpand"
IsEnabled="{Binding CurrentUserHasContact}">
<CheckBox IsChecked="{Binding CCEnable}" Color="{StaticResource Key=MainButtonPrimaryColor}"/>
<Label Text="Recevoir une copie" VerticalOptions="CenterAndExpand"/>
</StackLayout>
<StackLayout Padding="10,0,10,10">
<Button Style="{StaticResource Key=BtnFlex}" Text="Envoyer"
WidthRequest="100" HeightRequest="30"
Command="{Binding SendMailCommand}"/>
</StackLayout>
</StackLayout>
</Frame>
</telerikPrimitives:RadBorder>
</telerikPrimitives:RadPopup>
</telerikPrimitives:RadPopup.Popup>
And the contentView :
EntrySearchTiers = new SearchableEntry()
{
Style = (Xamarin.Forms.Style)Application.Current.Resources["MainEntryStyle"],
FontSize = FontSizeMedium,
Placeholder = "Liste des tiers"
};
EntrySearchTiers.Behaviors.Add(new Prism.Behaviors.EventToCommandBehavior
{
//EventName = "Completed", --> Jamais triggered
EventName = "TextChanged",
Command = TiersSelectedCommand
});
EntrySearchTiers.SetBinding(Entry.TextProperty, new Binding("CodeTiersSelected", BindingMode.TwoWay, null));
Base.Views.Popups.ChoicesPopup popup = new Base.Views.Popups.ChoicesPopup(_serviceTiers, null, Guid.Empty, EntrySearchTiers, "code tiers :", this, serviceHistoChoice: _serviceHistoChoice, groupChoice: Enums.enumGroupChoice.Tiers);
await popup.ActivateSearchEntryBehavior();
enter code here