public partial class MainPage : ContentPage
{
    private int _previousCursorPosition = 0;
    private int _previousTextLength = 0;
    private RadTextInput _autoCompleteTextInput;

    public MainPage()
    {
        InitializeComponent();
        // Wait for the control to load and then find the internal RadTextInput
        autoComplete.Loaded += AutoComplete_Loaded;
    }

    private void AutoComplete_Loaded(object sender, EventArgs e)
    {
        // Find the internal RadTextInput in the RadAutoComplete
        _autoCompleteTextInput = FindRadTextInputInVisualTree(autoComplete);

        if (_autoCompleteTextInput != null)
        {
            _autoCompleteTextInput.TextChanging += RadTextInput_TextChanging;
            _autoCompleteTextInput.TextChanged += RadTextInput_TextChanged;
        }
    }

    private RadTextInput FindRadTextInputInVisualTree(Element element)
    {
        if (element is RadTextInput textInput)
        {
            return textInput;
        }
        if (element is Layout layout)
        {
            foreach (var child in layout.Children)
            {
                var result = FindRadTextInputInVisualTree(child as Element);
                if (result != null)
                {
                    return result;
                }
            }
        }
        else if (element is ContentView contentView && contentView.Content != null)
        {
            return FindRadTextInputInVisualTree(contentView.Content as Element);
        }
        else if (element is ScrollView scrollView && scrollView.Content != null)
        {
            return FindRadTextInputInVisualTree(scrollView.Content as Element);
        }
        else if (element is ContentPage page && page.Content != null)
        {
            return FindRadTextInputInVisualTree(page.Content as Element);
        }

        var type = element.GetType();
        var childrenProperty = type.GetProperty("Children");
        var contentProperty = type.GetProperty("Content");

        if (childrenProperty != null)
        {
            var children = childrenProperty.GetValue(element);
            if (children is System.Collections.IEnumerable enumerable)
            {
                foreach (var child in enumerable)
                {
                    if (child is Element childElement)
                    {
                        var result = FindRadTextInputInVisualTree(childElement);
                        if (result != null)
                        {
                            return result;
                        }
                    }
                }
            }
        }
        else if (contentProperty != null)
        {
            var content = contentProperty.GetValue(element);
            if (content is Element contentElement)
            {
                return FindRadTextInputInVisualTree(contentElement);
            }
        }

        return null;
    }

    private void RadTextInput_TextChanged(object sender, TextChangedEventArgs e)
    {
        if (sender is RadTextInput textInput)
        {
            int newTextLength = e.NewTextValue?.Length ?? 0;
            int oldTextLength = e.OldTextValue?.Length ?? 0;
            int lengthDifference = newTextLength - oldTextLength;
            int expectedCursorPosition = _previousCursorPosition + lengthDifference;
            expectedCursorPosition = Math.Max(0, Math.Min(expectedCursorPosition, newTextLength));

            Dispatcher.Dispatch(() =>
            {
                textInput.CursorPosition = expectedCursorPosition;
            });

            _previousCursorPosition = expectedCursorPosition;
            _previousTextLength = newTextLength;
        }
    }

    private void RadTextInput_TextChanging(object sender, TextChangingEventArgs e)
    {
        if (sender is RadTextInput textInput)
        {
            _previousCursorPosition = textInput.CursorPosition;
            _previousTextLength = textInput.Text?.Length ?? 0;
        }
    }
}