private void ExecuteAddCommand()
        {
            var availible = AvailibleItems.ToList();
            var selected  = SelectedItems.ToList();

            foreach (var selectedItem in AvailibleListBox.SelectedItems)
            {
                availible.Remove((ISelectiveListItem)selectedItem);
                selected.Add((ISelectiveListItem)selectedItem);
            }

            AvailibleItems = availible;
            SelectedItems  = selected;
        }
        private void ExecuteRemoveAllCommand()
        {
            if (SelectedItems != null)
            {
                if (AvailibleItems != null)
                {
                    var availible = AvailibleItems.ToList();
                    availible.AddRange(SelectedItems);
                    AvailibleItems = availible;


                    var selected = SelectedItems.ToList();
                    selected.Clear();
                    SelectedItems = selected;
                }
            }
        }