or

Use the OnClientTabSelected property to specify a JavaScript function that will be executed after a tab is selected - either by left-clicking it with a mouse or hitting enter after tabbing to that tab.
Two parameters are passed to the handler

<telerik:RadGrid ID="rgOptions" runat="server" AutoGenerateColumns="False" ResolvedRenderMode="Classic" AllowMultiRowEdit="True"> <MasterTableView> <Columns> <telerik:GridBoundColumn DataField="KARAKTERTANIM" FilterControlAltText="Filter column column" HeaderText="Option" UniqueName="column"> </telerik:GridBoundColumn> <telerik:GridTemplateColumn FilterControlAltText="" HeaderText="Selection" UniqueName="TemplateColumn"> <ItemTemplate> <asp:HiddenField ID="hfKarakter" runat="server" Value = '<%# Eval("KARAKTER") %>'/> <asp:CheckBox ID="cbCanSelect" runat="server" Checked = '<%#bool.Parse( Eval("CANSELECT").ToString()) %>'/> </ItemTemplate> <HeaderTemplate> <telerik:RadButton ID="cbAllCanSelect" runat="server" ToggleType="CustomToggle" ButtonType="ToggleButton" AutoPostBack="false" onclienttogglestatechanged="toggleCanSelectCheckBoxes"> <ToggleStates> <telerik:RadButtonToggleState Text="" PrimaryIconCssClass="rbToggleCheckbox"> </telerik:RadButtonToggleState> <telerik:RadButtonToggleState Text="" PrimaryIconCssClass="rbToggleCheckboxFilled"> </telerik:RadButtonToggleState> <telerik:RadButtonToggleState Text="" PrimaryIconCssClass="rbToggleCheckboxChecked"> </telerik:RadButtonToggleState> </ToggleStates> </telerik:RadButton> </HeaderTemplate> </telerik:GridTemplateColumn> </Columns> </MasterTableView> </telerik:RadGrid>function toggleCanSelectCheckBoxes(sender, args) { //alert(sender.get_selectedToggleState().get_index()); var dataItems = $find('<%=rgOptions.ClientID%>').get_masterTableView().get_dataItems(); for (var i = 0; i < dataItems.length; i++) { var cb = dataItems[i].findControl("cbCanSelect"); alert(cb); if (cb != null) cb.checked = true; } }