Newbie : Subclassing a simple object crashes (vs express too)

Hi All i'm a NewBye

I want subclass a simple button.

i'm using the following code in a class library project to reate a dll:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ClassLibrary2
{
    publicclassbtnBase: System.Windows.Forms.Button
    {
        publicint myprop {
            get
            {
                return myprop;
            }
            set{
                myprop = value;
            }
        }
    }

} 

When i add the cmponent in the visual toolbox all seems ok.

but when i create a windows test project but when i try to add visually the control in to the form the ide crashes brutally ... this behaviour is the same on the vs express ... i tryed with sd version 4.4 and 5.0  but nothing change .... have i mistake something (other than my ugly english 8)) ?