CentralizedControl/HandyControl/HandyControl_Shared/Controls/Input/WatermarkTextBox.cs

using System.Windows;

namespace HandyControl.Controls;

public class WatermarkTextBox : TextBox
{
    #region Public Properties

    #region Watermark

    public static readonly DependencyProperty WatermarkProperty = DependencyProperty.Register(
        nameof(Watermark), typeof(object), typeof(WatermarkTextBox), new PropertyMetadata(default(object)));

    public object Watermark
    {
        get => GetValue(WatermarkProperty);
        set => SetValue(WatermarkProperty, value);
    }

    #endregion Watermark

    #endregion Public Properties

    protected override void OnGotFocus(RoutedEventArgs e)
    {
        base.OnGotFocus(e);
        if (IsEnabled)
        {
            if (!string.IsNullOrEmpty(Text))
            {
                Select(0, Text.Length);
            }
        }
    }
}