public void MoveUp()
{
if (SelectedColumns.Count == 0 || SelectedColumns.First().IsSelected)
{
return;
}
var selected = SelectedColumns.Where(c => c.IsSelected).ToArray();
foreach (var item in selected)
{
var index = SelectedColumns.IndexOf(item);
SelectedColumns.RemoveAt(index);
SelectedColumns.Insert(index - 1, item);
}
}
