C# Signature:

[ComImport]
[Guid ("f1db8392-7331-11d0-8c99-00a0c92dbfe8")]
[InterfaceType (ComInterfaceType.InterfaceIsIUnknown)]
public interface IInputObjectSite
{
     [PreserveSig] int OnFocusChangeIS (
               [MarshalAs (UnmanagedType.IUnknown)] ref object punkObj,
               [MarshalAs (UnmanagedType.Bool)] ref bool fSetFocus);
}