MemoryStream stream = new MemoryStream();
StreamWriter writer = new StreamWriter( stream );
 
writer.WriteLine("test");
 
writer.Flush();               // <= これが必要

using System;
using System.Windows.Forms;
 
using System.Runtime.InteropServices; //DllImport属性を使用するために必要
 
namespace WinFormTest1 {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
 
            // コンソールにログを出力
            writeConsole( "Form1() called" );
        }
 
        private void Form1_Load( object sender, EventArgs e ) {
            // コンソールにログを出力
            writeConsole( "Form1_Load called" );
        }
 
 
        [DllImport("kernel32.dll")]
        public static extern bool AttachConsole(uint dwProcessId);
 
        [DllImport("kernel32.dll")]
        public static extern bool FreeConsole();
 
        //*********************************************************************
        /// <summary> コンソールに文字を出力する
        /// 
        /// </summary>
        /// <param name="msg">  出力する文字列</param>
        /// <returns>           true:成功, false:失敗</returns>
        //*********************************************************************
        private bool writeConsole( string msg ) {
 
            if ( !AttachConsole( System.UInt32.MaxValue ) ) {
                return false;
            }
 
            // stdoutのストリームを取得
            System.IO.Stream       stream = System.Console.OpenStandardOutput();
            System.IO.StreamWriter stdout = new System.IO.StreamWriter( stream );
 
            // 指定された文字列を出力
            stdout.WriteLine( msg );
            stdout.Flush();
 
            FreeConsole();
            return true;
        }
    }
}

[Parameters]
dwProcessId [in]
 
ATTACH_PARENT_PROCESS　(DWORD)-1
Use the console of the parent of the current process.

using( StreamWriter writer = new StreamWriter( stream, Encoding.GetEncoding(932) ) ) {
	writer.Write( ... );
}

using( FileStream   stream = new FileStream( filename, FileMode.Create, FileAccess.Write, FileShare.None ) )
using( StreamWriter writer = new StreamWriter( stream, Encoding.GetEncoding(932) ) ) {
	writer.Write( ... );
}

//*********************************************************************
/// <summary> dan.co.jpのwebapiを使用してアマゾンの書籍情報を取得する
/// 
/// </summary>
/// <param name="asin">	検索キー(ASIN)</param>
/// <returns>書籍情報</returns>
//*********************************************************************-
private static XmlDocument searchItemInfoByAsin( string asin ) {
	string url = "http://api.dan.co.jp/asin/" + asin + ".xml";
	using (XmlReader reader = XmlReader.Create(url)) {
		XmlDocument doc = new XmlDocument();
		doc.Load( reader );
		return doc;
	}
}

//-----------------------
// 商品情報を取得する
//-----------------------
XmlDocument itemDoc = null;
try {
	itemDoc = searchItemInfoByAsin( "4534045220" );
} catch ( Exception ex ) {
	MessageBox.Show( "商品データの取得に失敗しました id[" + id + "]\n" + ex.Message );
	continue;
}
 
string asin     = getNodeTextDef( itemDoc, "/opt/ASIN",     "" );
string title    = getNodeTextDef( itemDoc, "/opt/ItemAttributes/Title",     "" );
string author   = getNodeTextDef( itemDoc, "/opt/ItemAttributes/Author",     "" );
string binding  = getNodeTextDef( itemDoc, "/opt/ItemAttributes/Binding",    "" );
string label    = getNodeTextDef( itemDoc, "/opt/ItemAttributes/Label",      "" );
string newPrice = getNodeTextDef( itemDoc, "/opt/ItemAttributes/ListPrice/FormattedPrice", "" );
string imageUrl = getNodeTextDef( itemDoc, "/opt/ImageSets/SwatchImage/URL", "" );
string linkUrl  = getNodeTextDef( itemDoc, "/opt/DetailPageURL", "" );
 
System.Console.WriteLine( asin     );
System.Console.WriteLine( title    );
System.Console.WriteLine( author   );
System.Console.WriteLine( binding  );
System.Console.WriteLine( label    );
System.Console.WriteLine( newPrice );
System.Console.WriteLine( imageUrl );
System.Console.WriteLine( linkUrl  );

//*********************************************************************
/// <summary> XmlDocumentから指定されたノードの情報を取得する
/// </summary>
/// <param name="doc">          取得対象のxml情報</param>
/// <param name="xpath">        取得するノードのxpath式</param>
/// <param name="defaultValue"> 指定したノードが無かったときの値</param>
/// <returns>ノードのテキスト(InnerXml)</returns>
//*********************************************************************
private static string getNodeTextDef( XmlDocument doc, string xpath, string defaultValue ) {
    XmlNode node = doc.SelectSingleNode( xpath );
    if ( node == null ) {
        return defaultValue;
    } else {
        return node.InnerText;
    }
}

//---------------------------------------------------------------------------
/// <summary>
/// 指定されたURLの画像をImage型オブジェクトとして取得する
/// </summary>
/// <param name="url">画像データのURL(ex: http://example.com/foo.jpg) </param>
/// <returns>         画像データ</returns>
//---------------------------------------------------------------------------
public static System.Drawing.Image loadImageFromURL( string url ) { 
    int buffSize = 65536; // 一度に読み込むサイズ
    MemoryStream imgStream = new MemoryStream();
 
    //------------------------
    // パラメータチェック
    //------------------------
    if ( url == null || url.Trim().Length <= 0 ) {
        return null;
    }
 
    //----------------------------
    // Webサーバに要求を投げる
    //----------------------------
    WebRequest req = WebRequest.Create( url );
    BinaryReader reader = new BinaryReader( req.GetResponse().GetResponseStream() );
 
    //--------------------------------------------------------
    // Webサーバからの応答データを取得し、imgStreamに保存する
    //--------------------------------------------------------
    while ( true ) {
        byte[] buff = new byte[ buffSize ];
 
        // 応答データの取得
        int readBytes = reader.Read( buff, 0, buffSize );
        if ( readBytes <= 0 ) {
            // 最後まで取得した->ループを抜ける
            break;
        }
 
        // バッファに追加
        imgStream.Write( buff, 0, readBytes );
    }
 
    return new Bitmap( imgStream );
}

button1.SetFocus();

1.親画面からForm.Show()メソッド(又はShowDialog)をコールする
↓
2.子画面のOnLoad()イベントが指定されていたら、実行する
↓
3.子画面に配置されているコントロールのTabStopをチェックし、初期フォーカスをセットする
↓
4.子画面が開く

private void Form1_Load(object sender, System.EventArgs e) {
  // 初期フォーカスをセット
  ActiveControl = button1;
}

---------------
Overview
---------------
The Microsoft Reference Source License (MS-RSL) is the most restrictive of the Microsoft 
source code licenses. The license prohibits all use of source code other than the viewing 
of the code for reference purposes. The intent of this license is to enable licensors to 
release, for review purposes only, more sensitive intellectual property assets.
 
Microsoft commonly uses this license for developer libraries where modification is not 
required to make use of the source code. In these cases, the importance of transparency 
is based on the need for developers to more deeply understand the inner workings of the 
source code. In doing so, the licensees will be more effective in writing software that 
makes use of the licensed source code.
 
The copyright and patent grants in this license are both royalty free, meaning that the 
licensee does not have to pay anything to the licensor to make use of the source code. 
The license limits the source code release to use on the Windows platform only. 
Microsoft cannot provide legal advice on the use or implications of this license. 
We recommend that developers obtain appropriate legal advice before deciding
how to license their source code.
 
The source code for the .NET Framework libraries are released under a modified 
Microsoft Reference Source License.
 
---------------
Terms of Use
---------------
Developers who wish to access source code under the Reference Source Program must 
agree to the license that accompanies the code.
Licensees may use the source code to assist with the development of commercially distributed products.
Licensees may not modify or redistribute the source code.
 
 
-------------------------
Eligibility Requirements
-------------------------
There are no eligibility requirements for this program. Everyone who agrees to the 
accompanying license may use the source code provided under the Reference Source Program.