C#

private void Logging()
        {

        
            SaveFileDialog saveFileDialog1 = new SaveFileDialog();
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                using (Stream s = File.Open(saveFileDialog1.FileName, FileMode.CreateNew | FileMode.Append))
                using (StreamWriter sw = new StreamWriter(s))
                {
                    
                    sw.WriteLine(textSampling.Text);
                    
                }
                   

            }

SaveFileDialog saveFileDialog1 = new SaveFileDialog();
                if (saveFileDialog1.ShowDialog() == DialogResult.OK)
                {
                    using (Stream s = File.Open(saveFileDialog1.FileName,FileMode.CreateNew))
                    using (StreamWriter sw = new StreamWriter(s))
                    {

                        sw.WriteLine(textSensorValues.Text);

                    }


                }

Item item = new Item();
myPanel.Controls.Add(item);

myPanel.Controls.Remove(item);
item.Dispose();

void IDisposable.Dispose() {
    if (hBitmapDC.Handle == IntPtr.Zero || hMetafileDC.Handle == IntPtr.Zero || hBitmap.Handle == IntPtr.Zero) {
        return;
    }

    bool success;

    try {
        success = DICopy(hMetafileDC, hBitmapDC, destRect, true);
        Debug.Assert(success, "DICopy() failed.");
        SafeNativeMethods.SelectObject(hBitmapDC, hOriginalBmp);
        success = SafeNativeMethods.DeleteObject(hBitmap);
        Debug.Assert(success, "DeleteObject() failed.");
        success = UnsafeNativeMethods.DeleteCompatibleDC(hBitmapDC);
        Debug.Assert(success, "DeleteObject() failed.");
    }
    finally {

        // Dispose is done. Set all the handles to IntPtr.Zero so this way the Dispose method executes only once.
        hBitmapDC = NativeMethods.NullHandleRef;
        hBitmap = NativeMethods.NullHandleRef;
        hOriginalBmp = NativeMethods.NullHandleRef;

        GC.SuppressFinalize(this);
    }
}

TextBox tbx = new TextBox { Text = "wtf" };

this.Controls.Add(tbx);

var c1  = this.Controls.Count;

tbx.Dispose();

var c2 = this.Controls.Count; // yep, one less

bool isnull = tbx == null;  // => false

=/// <summary>Releases all resources used by the <see cref="T:System.ComponentModel.Component" />.</summary>
public void Dispose()
{
  this.Dispose(true);
  GC.SuppressFinalize((object) this);
}

Key point: Controls added to a ControlCollection and docked 'Top followed by the use of 'BringToFront on the Control will be added beneath other controls. When one of these controls is removed/deleted, the other Controls will rearrange so that the order is maintained.

Quote:

a.1. set event handlers for the ToDo close-button Click, and checkbox CheckStateChanged, events.

public ToDo()
{
    InitializeComponent();
    CbxDone = cbxDone;
    LblID = lblId;
    BtnClose = btnClose;
    TxtBx = textBox1;
}

public CheckBox CbxDone { set; get; }
public Label LblID { set; get; }
public Button BtnClose { set; get; }
public TextBox TxtBx { set; get; }

private void btnAdd_Click(object sender, EventArgs e)
{
    ToDo todo = new ToDo();
    currentToDos.Add(todo);  // a list of all hosted controls
    currentToDo = todo;      // current hosted vontrol

    todo.LblID.Text = (idCount).ToString();
    idCount++;

    // attach the EventHandlers
    todo.Enter += TodoOnEnter;
    todo.Leave += TodoOnLeave;

    todo.BtnClose.Click += BtnCloseOnClick;

    todo.CbxDone.CheckStateChanged += CbxDoneOnCheckStateChanged;
    
    todopanel.Controls.Add(todo);
    todo.Dock = DockStyle.Top;
    todo.BringToFront();

    this.ActiveControl = todo;
}

currentToDos.Remove(currentToDo);
this.todopanel.Controls.Remove(currentToDo);
currentToDo.Dispose();

this.Invalidate();