[Mono-list] Marshaling works with Mono .16 but not Mono .18

[Colin Francis Branch]

I'm using Interop for a NET port of SDL and I have it working in linux
using mono .16 but I get a marshaling error when I try and run it with
mono .18

The problem is in marshaling strings, which I due like
[DLLImport(DLLNAME)]
public static extern void
SDL_SW_SetCaption([MarshalAs(UnmanagedType.LPStr)]string
title,[MarshalAs(UnmanagedType.LPStr)]string icon);

The error I receive is:

Warning: Marshaling Conversion not supported
Error: line 2170 in marshal.c should not be reached

I'm wondering why this would work in .16 and not .18.  If it how I'm
marshaling strings or has marshalling support been removed.

Any help would be appreciated.

Thanks
Colin Branch
(SDLSharp.sourceforge.net for (very little) project info)