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();

using (StreamReader r = new StreamReader(LoadFileOnStart, System.Text.Encoding.Default))
        MainTextArea.Rtf = r.ReadToEnd();

<br />
Example<br />
// cs_using_statement.cs<br />
// compile with /reference:System.Drawing.dll<br />
using System.Drawing;<br />
class a<br />
{<br />
   public static void Main()<br />
   {<br />
      using (Font MyFont = new Font("Arial", 10.0f), MyFont2 = new Font("Arial", 10.0f))<br />
      {<br />
         // use MyFont and MyFont2<br />
      }   // compiler will call Dispose on MyFont and MyFont2<br />
<br />
<br />
<br />
<br />

<br />
if(LoadFileOnStart.ToLower().EndsWith("rtf")|LoadFileOnStart.ToLower().EndsWith("doc")){<br />
using (StreamReader r = new StreamReader(LoadFileOnStart,System.Text.Encoding.Default)){<br />
MainTextArea.Rtf = r.ReadToEnd();<br />
	r.Close();<br />
      }<br />
  }<br />