C#

public class ClosableTabCtrl : TabControl
{
#region Private Members
    private System.Windows.Forms.ImageList buttonImageList;

    private bool showCloseButton = true;
    private bool hideCloseButtonWhenOnlyOneTab;

    private const string tabText = "      ";

    private int buttonImageIndex;
#endregion

    public ClosableTabCtrl() : base()
    {
        buttonImageList = new ImageList();

        buttonImageList.Images.Add((Image)new Bitmap(Resources.InactiveCross));
        buttonImageList.Images.Add((Image)new Bitmap(Resources.ActiveCross));
        buttonImageList.Images.Add((Image)new Bitmap(Resources.ClickedCross));

        this.DrawMode = TabDrawMode.OwnerDrawFixed;
        this.DrawItem += new DrawItemEventHandler(ClosableTabCtrl_DrawItem);

        this.MouseMove += new MouseEventHandler(ClosableTabCtrl_MouseMove);
        this.MouseLeave += new EventHandler(ClosableTabCtrl_MouseLeave);
        this.MouseClick += new MouseEventHandler(ClosableTabCtrl_MouseClick);
        this.MouseDown += new MouseEventHandler(ClosableTabCtrl_MouseDown);
        this.MouseUp += new MouseEventHandler(ClosableTabCtrl_MouseUp);

        SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
        SetStyle(ControlStyles.AllPaintingInWmPaint, true);
    }

    void ClosableTabCtrl_MouseUp(object sender, MouseEventArgs e)
    {
        if (MouseIsOverButton(e) && buttonImageIndex != 1)
        {
            buttonImageIndex = 1;
            this.Invalidate();
        }
    }

    void ClosableTabCtrl_MouseDown(object sender, MouseEventArgs e)
    {
        if (MouseIsOverButton(e) && buttonImageIndex != 2)
        {
            buttonImageIndex = 2;
            this.Invalidate();
        }
    }

    void ClosableTabCtrl_MouseClick(object sender, MouseEventArgs e)
    {
        if (MouseIsOverButton(e))
        {
            // TODO: raise the event
        }

    }

    void ClosableTabCtrl_MouseLeave(object sender, EventArgs e)
    {
        if (buttonImageIndex != 0)
        {
            buttonImageIndex = 0;
            this.Invalidate();
        }
    }

    void ClosableTabCtrl_MouseMove(object sender, MouseEventArgs e)
    {
        if (MouseIsOverButton(e))
        {
            if (buttonImageIndex != 1)
            {
                buttonImageIndex = 1;
                this.Invalidate();
            }
        }
        else
        {
            if (buttonImageIndex != 0)
            {
                buttonImageIndex = 0;
                this.Invalidate();
            }
        }
    }

    public bool ShowCloseButton
    {
        get { return showCloseButton; }
        set { showCloseButton = value; }
    }

    public bool HideCloseButtonWhenOnlyOneTab
    {
        get { return hideCloseButtonWhenOnlyOneTab; }
        set { hideCloseButtonWhenOnlyOneTab = value; }
    }

    bool MouseIsOverButton(MouseEventArgs e)
    {
        Rectangle r = this.GetTabRect(this.SelectedIndex);
        r.Offset(2, 2);
        Rectangle b = new Rectangle(new Point(r.X + (this.GetTabRect(this.SelectedIndex).Width - 20), this.GetTabRect(this.SelectedIndex).Height / 2 - 7),
                                    new Size(17, 17));

        if (b.Contains(e.Location))
        {
            return true;
        }
        else
        {
            return false;
        }
    }


    void ClosableTabCtrl_DrawItem(object sender, DrawItemEventArgs e)
    {
        Rectangle r = this.GetTabRect(e.Index);
        string title = String.Empty;

        r.Offset(2, 2);
        Brush TitleBrush = new SolidBrush(Color.Black);
        Font f = this.Font;

        if (e.State == DrawItemState.Selected)
        {
            if (!this.TabPages[e.Index].Text.EndsWith(tabText))
            {
                this.TabPages[e.Index].Text += tabText;
            }
            title = this.TabPages[e.Index].Text + tabText;


            if (showCloseButton)
            {
                if (!(this.hideCloseButtonWhenOnlyOneTab && this.TabPages.Count == 1))
                {
                    e.Graphics.DrawImage(buttonImageList.Images[buttonImageIndex],
                                         new Point(r.X + (this.GetTabRect(e.Index).Width - 20),
                                             this.GetTabRect(e.Index).Height / 2 - 7));
                }
            }
        }
        else
        {
            if (this.TabPages[e.Index].Text.EndsWith(tabText))
            {
                this.TabPages[e.Index].Text = this.TabPages[e.Index].Text.Replace(tabText, string.Empty);
            }

            title = this.TabPages[e.Index].Text + tabText;
        }
        // center the text in the tab
        e.Graphics.DrawString(title, f, TitleBrush, new PointF(r.X, (r.Height - f.Height) / 2 + 1));

        TitleBrush.Dispose();
    }
}

    using (System.IO.MemoryStream saveStream = new System.IO.MemoryStream())
    {
/*Ex*/  System.Xml.Serialization.XmlSerializer saveSerializer = new System.Xml.Serialization.XmlSerializer(typeof(MyFineCollection));
        saveSerializer.Serialize(saveStream, _manyObjects);
    }

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace Test_Xml
{
    public class MyFantasticBaseClass
    {
        private int _id = 0;

        public MyFantasticBaseClass(int id)
        {
            this._id = id;
        }

        public int Id
        {
            get { return (_id); }
        }
    }


    public class FirstDerivedClass : MyFantasticBaseClass
    {
        private bool _isReallyUseful = true;

        public bool IsReallyUseful
        {
            get { return (_isReallyUseful); }
            set { _isReallyUseful = value; }
        }
    }


    public class SecondDerivedClass : MyFantasticBaseClass
    {
        private double _zoom = 1.0;
        private MyFantasticBaseClass _linkedElement = null;

        public double Zoom
        {
            get { return (_zoom); }
            set { _zoom = value; }
        }

        public MyFantasticBaseClass LinkedElement
        {
            get { return (_linkedElement); }
            set { _linkedElement = value; }
        }
    }


    public class MyFineCollection:ICollection<MyFantasticBaseClass>
    {
        List<MyFantasticBaseClass> _innerList = new List<MyFantasticBaseClass>();

        // ICollection implementation details
    }
}

Class A
{
void CallingFunction()
{
    string data = "";
    DataTable dttemp = new DataTable();
    bool isValid = false;
    checkValue(ref data,ref isValid, ref dttemp);

    //perform some operation on data, dttemp
}

private void checkValue(ref string msg, ref bool valid, ref DataTable dttemp)
{
     msg += "Hello";
     valid = false;

     DataRow dr = dttemp.NewRow();
     dr["cID"] = "2";
     dttemp.Rows.Add(dr);
 }
}

Class A
{

DataTable dttemp;
string data = "";
bool isValid = false;

void CallingFunction()
{    
    dttemp = new DataTable();    
    checkValue();

    //perform some operation

    //reset them
    data = "";isValid = false; dttemp.Dispose();
}

private void checkValue()
{
     data += "Some data";
     isValid = true;

     DataRow dr = dttemp.NewRow();
     dr["cID"] = "2";
     dttemp.Rows.Add(dr);
 }
}