Creating Undo Button for RadListBox

[Caleb]

I was told to add an undo button for the RadListBox that will track and then revert he changes a user makes. I have the code set up but I am getting undefined errors in dynmiac code when it is running through transferItem(). I am not entirely sure whats going wrong with it. If someone could look and give some advice that would be great.

var UndoList = new Array();
function onClientTransferring(sender, e) {
    var items = e.get_items();
    for (var i = 0; i < items.length; i++) {
        var item = items[i];
        if (item.get_text() != "Select" || item.get_value() != "") {
            UndoList.push(item);
            UndoList.push(e.get_sourceListBox());
            UndoList.push(e.get_destinationListBox());
        }
    }
}
function undoChanges() {
    if (UndoList[UndoList.length - 1]._clientStateFieldID == "rlbStations_ClientState") {
    var listbox = $find('rlbStations');
    }
else if (UndoList[UndoList.length - 1]._clientStateFieldID == "rlbAllowedStations_ClientState") {
    var listbox = $find('rlbAllowedStations');
    }
    listbox.transferItem(UndoList[UndoList.length - 3], UndoList[UndoList.length - 1], UndoList[UndoList.length - 2]);
}

<telerik:RadListBox ID="rlbStations" runat="server" AllowTransfer="True" TransferToID="rlbAllowedStations" Height="200px" Skin="Web20" SelectionMode="Multiple" Sort="Ascending" DataKeyField="station_id"
 AutoPostBackOnTransfer="true" Width="250px" OnClientTransferring="onClientTransferring"
OnTransferred="rlbStations_Transferred"><ButtonSettings ShowDelete="False" ShowReorder="False" /> </telerik:RadListBox>
<asp:Button Text="Undo" runat="server" OnClientClick="undoChanges()" /><telerik:RadListBox ID="rlbAllowedStations" runat="server" Height="200px" Width="250px" Skin="Web20"> </telerik:RadListBox>

[Dimitar Terziev]

Hi Caleb,

Could you please open a support ticket and provide a runnable sample so we could test it locally?

All the best,
Dimitar Terziev
the Telerik team