public void ToggleSort(HeaderTextVisual v, bool add)
{
// Order: None -> Ascending -> Descending -> Ascending -> Descending -> ...
v.ToggleSortOrder();
if (add)
{
// Shift+Click adds column to the sorting set.
_sortOrder.Add(v);
}
else
{
// Clear all column sorts except the one that was clicked on.
ResetSortToPrimary(v);
_sortOrder.ResetTo(v);
}
SortOrderChanged?.Invoke(this, EventArgs.Empty);
}