Editable Multipleselectcombobox in wpf

Hi all,

i am using wpf(mvvm).actually i  have a combobox, this combobox selecting one item only and this combox able to edit to search the items. i need multipleselect items and edit to search items in combobox.

now i am using code is in View

<StackPanel HorizontalAlignment="Left" Grid.Row="0" Grid.Column="1" Width="227">

 <ComboBox Name="cRegionFilter" Text="{Binding ComboText}" StaysOpenOnEdit="True" IsEditable="True" SelectedItem="{Binding SelectedRegion}" DisplayMemberPath="RegionCd" SelectedIndex="{Binding ClearSelection}" SelectedValuePath="RegionCd" ItemsSource="{Binding FilterRegionName,Mode=TwoWay}" Grid.Column="3" Margin="0,0,0,0" Grid.RowSpan="2" Height="30" Width="100" HorizontalAlignment="Left"></ComboBox>

        </StackPanel>

view model

private List<CustomerMgmt> _filterRegionName;

_filterRegionName = new List<CustomerMgmt>();

    public List<CustomerMgmt> FilterRegionName
        {
            get { return _filterRegionName; }
            set
            {
                _filterRegionName = value;
                RaisePropertyChanged("FilterRegionName");
            }
        }   private void LoadRegionComboBox()
        {
            if (CustDisplay != null)
            {
                if (CustDisplay.CustomerCountry != null)
                {
                    var custRegion = (from list in CustDisplay.CustomerCountry select list.RegionCode).Distinct().ToList();
                    var filteredList = (from list in custRegion select new CustomerMgmt { RegionCd = list });
                    if (FilterRegionName != null) FilterRegionName.Clear();
                    FilterRegionName = filteredList.OrderBy(x => x.RegionCd).ToList();
                }
            }
        }