[Gtk-sharp-list] What's the trick to building an Art.Vpath ?

[Tim Day]

When I try:

  Art.Vpath vpath=new Art.Vpath();
  int pts;
  int pts_max;
  vpath.AddPoint(out pts,out pts_max,Art.Pathcode.Moveto,0.0,0.0);

it throws like this:

Unhandled Exception: System.NullReferenceException: Object reference not
set to an instance of an object
in (unmanaged) (wrapper managed-to-native) Art.Vpath:art_vpath_add_point
(Art.Vpath&,int&,int&,int,double,double)
in <0x00004> (wrapper managed-to-native) Art.Vpath:art_vpath_add_point
(Art.Vpath&,int&,int&,int,double,double)
in <0x00025> Art.Vpath:AddPoint (int&,int&,Art.Pathcode,double,double)
...

The whole pts & pts_max thing suggests I should be reserving some space
or something, but there's only a scary looking
  public static Vpath New (System.IntPtr raw)
member which looks even remotely related.

I'm using mono 1.0.5.  

Thanks for any help
Tim