C#

public class MyUpDown : NumericUpDown
    {
    public override void UpButton()
        {
        decimal save = Increment;
        if ((Control.ModifierKeys & Keys.Shift) == Keys.Shift)
            {
            Increment *= 10;
            }
        base.UpButton();
        Increment = save;
        }
    public override void DownButton()
        {
        decimal save = Increment;
        if ((Control.ModifierKeys & Keys.Shift) == Keys.Shift)
            {
            Increment *= 10;
            }
        base.DownButton();
        Increment = save;
        }
    }

class ExtendedUserControl : MyUserControl {
 // etc
}

public partial class PricePanelBase : UserControl
{
    public PricePanelBase()
    {
        InitializeComponent();
        InstallControls();
    }

    protected virtual void GetControls(ControlCollection Ctrls)
    {
    }

    private int InstallControls()
    {
        ControlCollection Ctrls = new ControlCollection(CPanel);

        GetControls(Ctrls);

        foreach (Control Ctrl in Ctrls)
            CPanel.Controls.Add(Ctrl);

        return Ctrls.Count;
    } ...

public partial class PricePanel : PricePanelBase
{
    public PricePanel()
    {
        InitializeComponent();
    }

    protected override void GetControls(ControlCollection Ctrls)
    {
        DataGridView GrdVw = new DataGridView();

        GrdVw.Name = "dataGridView1";
        GrdVw.Location = new Point(3, 35);
        GrdVw.Size = new Size(438, 146);

        Ctrls.Add(GrdVw);
    }...