ISynchronizeInvoke.cs

using System.Security.Permissions;

namespace System.ComponentModel
{
    public interface ISynchronizeInvoke
    {
        bool InvokeRequired
        {
            get;
        }

        [HostProtection(SecurityAction.LinkDemand, Synchronization = true, ExternalThreading = true)]
        IAsyncResult BeginInvoke(Delegate method, object[] args);

        object EndInvoke(IAsyncResult result);

        object Invoke(Delegate method, object[] args);
    }
}