Private m_XPanderComparer As XPanderComparer
Private m_ControlList As New SortedList(m_XPanderComparer)

…

‘ Add control to control list
e.Control.Tag = m_NextControlKey
m_NextControlKey += 1
m_ControlList.Add(e.Control.Tag, e.Control)

‘ VB.NET IComparer implmementation
Public Class XPanderComparer
    Implements IComparer

    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
        Dim xp1 As XPander = CType(x, XPander)
        Dim xp2 As XPander = CType(y, XPander)
        Dim result As Integer = 0

        If xp1.Top < xp2.Top Then result = -1
        If xp1.Top > xp2.Top Then result = 1

        Return result
    End Function
End Class

private XpanderComparer _xpanderComparer = new XpanderComparer();
private SortedList _controlList;

…

// Add control to control list
e.Control.Tag = _nextControlKey;
_nextControlKey += 1;
_controlList.Add( e.Control.Tag, e.Control );

// C# IComparer implementation
public class XpanderComparer : IComparer
{

    #region IComparer Members

    public int Compare(object x, object y) 
    {
        try 
    {
        XpanderControl xpander1 = (XpanderControl)x; <=== InvalidCastException
    XpanderControl xpander2 = (XpanderControl)y;
    int result = 0;

    if( xpander1.Top < xpander2.Top )
        result = -1;
    if( xpander1.Top > xpander2.Top )
        result = 1;

    return result;

    } 
    catch (Exception e) 
    {
        MessageBox.Show(e.ToString());
        return 0;
    }
    }

    #endregion

    }