Snipplet to create a custom property

using EPiServer.Core;
using EPiServer.PlugIn;

namespace EPiServer.Templates
{
    [PageDefinitionTypePlugIn(
        DisplayName = "My Property",
        Description = "",
        SortIndex = 1)]
    public class MyProperty : PropertyString
    {
        public override object Value
        {
            get { return base.Value; }
            set { base.Value = value; }
        }
    }
}

using System;
using EPiServer.Web.PropertyControls;
using System.Web.UI.WebControls;

namespace EPiServer.Templates
{
    public class MyPropertyControl : PropertyStringControl
    {
        TextBox _inputControl;
 
        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            _inputControl = new TextBox();
            _inputControl.Text =
                ((string)PropertyData.Value) ?? String.Empty;
        }

        public override void CreateEditControls()
        {
            Controls.Add(_inputControl);
        }

        public override void ApplyEditChanges()
        {
            if (!String.IsNullOrEmpty(_inputControl.Text))
            {
                SetValue(_inputControl.Text);
            }
        }
    }
}