void ResetCachedData()
{
Concurrency.LockFreeUpdate(ref m_SortedVisibleColumns, Columns.SortedVisibleColumns.ToArray());
var lst = new BinarySortedList <float> ();
float offset = 0;
Columns.Where(col => col.Visible).ForEach(col => {
lst.AddLast(offset);
offset += col.Width;
});
Concurrency.LockFreeUpdate(ref m_ColumnOffsets, lst);
}