public class CollectionViewPlatformHandler : CollectionViewHandler
    {
        /// <inheritdoc />
        protected override UIView CreatePlatformView()
        {
            var platformView = base.CreatePlatformView();
            if (ItemsView.IsGrouped && ItemsView.ItemsSource is IEnumerable<IGrouping<string, object>> groups && platformView.Subviews[0] is UICollectionView collectionView)
            {
                // Enable index titles.
                collectionView.DataSource = new GroupedCollectionViewDataSource(collectionView.DataSource, groups.Select(q => q.Key));
            }

            return platformView;
        }
        
        private class GroupedCollectionViewDataSource(IUICollectionViewDataSource datasource, IEnumerable<string> sections) : UICollectionViewDataSource
        {
            public override nint NumberOfSections(UICollectionView collectionView) => datasource.NumberOfSections(collectionView);
            public override nint GetItemsCount(UICollectionView collectionView, nint section) => datasource.GetItemsCount(collectionView, section);
            public override UICollectionViewCell GetCell(UICollectionView collectionView, NSIndexPath indexPath) => datasource.GetCell(collectionView, indexPath);
            public override UICollectionReusableView GetViewForSupplementaryElement(UICollectionView collectionView, NSString elementKind, NSIndexPath indexPath) => datasource.GetViewForSupplementaryElement(collectionView, elementKind, indexPath);
            public override string[] GetIndexTitles(UICollectionView collectionView) => sections.ToArray();
        }
    }

<MauiVersion>8.0.20-nightly.10376</MauiVersion>

<Style TargetType="telerik:RadTimePicker">
    <Setter Property="PopupSettings">
        <Setter.Value>
            <telerik:PickerPopupSettings IsHeaderVisible="False" />
        </Setter.Value>
    </Setter>
</Style>

Name
Value
Type
◢
InnerException
{"Object reference not set to an instance of an object."}
System.Exception {System.NullReferenceException}
at Microsoft.Maui.Controls.AppThemeBinding.AppThemeProxy..ctor(Element parent, AppThemeBinding binding)
   at Microsoft.Maui.Controls.AppThemeBinding.Apply(Object context, BindableObject bindObj, BindableProperty targetProperty, Boolean fromBindingContextChanged, SetterSpecificity specificity)
   at Microsoft.Maui.Controls.BindableObject.SetBinding(BindableProperty targetProperty, BindingBase binding, SetterSpecificity specificity)
   at Microsoft.Maui.Controls.BindableObject.SetBinding(BindableProperty targetProperty, BindingBase binding)
   at Microsoft.Maui.Controls.BindableObjectExtensions.SetAppTheme[T](BindableObject self, BindableProperty targetProperty, T light, T dark)
   at Microsoft.Maui.Controls.BindableObjectExtensions.SetAppThemeColor(BindableObject self, BindableProperty targetProperty, Color light, Color dark)
   at Telerik.Maui.Controls.PickerPopupSettings.OnPopupOutsideBackgroundColorPropertyChanged(Color color)
   at Telerik.Maui.Controls.PickerPopupSettings..ctor()
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean wrapExceptions)

	<VerticalStackLayout>
		<telerik:RadEntry  x:Name="entry" Placeholder="telerik entry" BackgroundColor="AntiqueWhite" />
		<telerik:RadEntry x:Name="myentry" Placeholder="telerik entry" BackgroundColor="AntiqueWhite" />
		<Entry Placeholder="maui entry" BackgroundColor="LightBlue"/>
		<Entry Placeholder="maui entry" BackgroundColor="LightBlue"/>
	</VerticalStackLayout>