在键盘焦点和鼠标悬停时在工具提示中显示IDataErrorInfo错误

public class Person : IDataErrorInfo
{
    public string Name { get; set; }
    public int Age { get; set; }

    public string Error => this[string.Empty];

    public string this[string columnName]
    {
        get
        {
            string error = null;
            switch (columnName)
            {
                case nameof(Name):
                    if (string.IsNullOrEmpty(Name))
                        error = "Name is required.";
                    break;
                case nameof(Age):
                    if (Age <= 0 || Age >= 150)
                        error = "Age must be between 1 and 149.";
                    break;
            }
            return error;
        }
    }
}

<TextBox Text="{Binding Name, ValidatesOnDataErrors=True}" ToolTip="{Binding Name, ValidatesOnDataErrors=True}" />
<TextBox Text="{Binding Age, ValidatesOnDataErrors=True}" ToolTip="{Binding Age, ValidatesOnDataErrors=True}" />