Telerik rad control :Listbox

[Ashwnai]

Hi i am using telerik rad ListBox ,everything working fine but in my case a person can select different no of item ,so the value based on the role of user.
so i just want to know that how can i restrict a user to add more than 'X' items from list.
(Example if user="Admin" maximum no ="4";) 
Thanks in advance

code is as 

<telerik:RadListBox runat="server" ID="rlbSourceWeeklyOff" Height="200px" Width="200px"
                                    AllowTransfer="true" TransferToID="rlbDestinationWeeklyOff" >
                                </telerik:RadListBox>
                                <telerik:RadListBox runat="server" ID="rlbDestinationWeeklyOff" Height="200px" Width="200px">
                                </telerik:RadListBox>

[Peter Filipov]

Hi Ashwnai,

Please review the following sources - client side collection object and client side events (transfer events).

Kind regards,
Peter Filipov
the Telerik team