protected override void OnMouseEnter(EventArgs e)
{
    ...
    base.OnMouseEnter(e);
}

protected override void OnDrawItem(System.Windows.Forms.DrawItemEventArgs e)
{
    e.DrawBackground();
    Brush myBrush = Brushes.Black;
    switch (e.Index)
    {
         case  0 :
	myBrush = Brushes.Red;
	break;
         case  1 :
	myBrush = Brushes.Orange;
	break;
         case  2 :
	myBrush = Brushes.Purple;
	break;
    }
    e.Graphics.DrawString(this.Items[e.Index].ToString(), e.Font,
 myBrush,e.Bounds,StringFormat.GenericDefault);
    e.DrawFocusRectangle();
    base.OnDrawItem(e);
}