C#

    Private _mouseDown As Boolean<br />
    Private _lastY As Integer<br />
<br />
    Private Sub Panel1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseDown<br />
        _mouseDown = True<br />
        _lastY = e.Y<br />
    End Sub<br />
<br />
    Private Sub Panel1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseMove<br />
        If _mouseDown Then<br />
            Dim y As Integer<br />
            If e.Y > _lastY Then<br />
                y = e.Y - _lastY<br />
                Panel1.AutoScrollPosition = New Point(Panel1.AutoScrollPosition.X, y)<br />
            ElseIf e.Y < _lastY Then<br />
                y = _lastY - e.Y<br />
                Panel1.AutoScrollPosition = New Point(Panel1.AutoScrollPosition.X, y)<br />
            End If<br />
        End If<br />
    End Sub<br />
<br />
    Private Sub Panel1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseUp<br />
        _mouseDown = False<br />
    End Sub

public class MyData
{
    protected string myText;
    public event EventHandler MyTextChanged;

    public string MyText
    {
        get {return myText;}
        set
        {
            myText=value;
            if (MyTextChanged != null)
            {
                MyTextChanged(this, EventArgs.Empty);
            }
        }
    }

    public MyData()
    {
        myText="Initial Value";
    }
}