C#

private string pcname = ".";

[Category("Interface Options")]
[TypeConverter(typeof(ControlOptions.MachineConvertor))]
public string MachineName 
{
   get {return pcname;}
   set {pcname = value;
      sname = value;
   }
}

[DllImport("Netapi32")]
private static extern int NetServerEnum(
   string servername, //must be null
   int level, //101
   out int buffer,
   int maxlen, //out
   out int entriesread, //out
   out int totalentries, //out
   int servertype, //in 3 = all
   string domain, //null primary
   int resumehandle); //must be 0

[DllImport("Netapi32")]
private static extern int NetApiBufferFree(IntPtr ptr);

[StructLayout(LayoutKind.Sequential)]
class ServerInfo 
{
   public int platformid;
   [MarshalAs(UnmanagedType.LPWStr)]
   public string name;
   public int majorver;
   public int minorver;
   public int type;
   [MarshalAs(UnmanagedType.LPWStr)]
   public string comment;
}

class MachineConvertor : TypeConverter 
{
   public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
   {
      int eread, etot, buffer;
      int l = 20;     
      int size = Marshal.SizeOf(typeof(ServerInfo));
      int res = NetServerEnum(
         null, 
         101, 
         out buffer, 
         size * l, 
         out eread, 
         out etot, 
         3, 
         null, 
         0);
            
      int  p = buffer;
      ArrayList arr = new ArrayList(etot);
      for (int i = 0; i < eread; i++)
      {
         ServerInfo si = Marshal.PtrToStructure((IntPtr) p, typeof(ServerInfo)) as ServerInfo;   
         arr.Add(si.name);
         p += size;
      }
      
      res = NetApiBufferFree((IntPtr) buffer);
      return new StandardValuesCollection(arr);
   }

   public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
   {
      return true;
   }
}

frmPISmain.Hide();

frmPISContact childForm = new frmPISContact();
childForm.Show();