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RadCombo Scroll Position

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ComboBox
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Tracy
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Tracy asked on 18 Oct 2012, 01:42 PM
Hi,

I have a radcombobox with checkboxes and am using multiselect.  I am using the server side on click event which of course is causing a postback.  With this in mind is it possible to maintain the scroll position in the rad combo box. 
For example,  if I check the 54th item in the list it then returns me back to the top of the list.  I would like it to return to the item that I checked.

Thank you for your help.
Tracy

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Kalina
Telerik team
answered on 22 Oct 2012, 01:09 PM
Hello Tracy,

I am afraid that updating the scroll position to the last checked item after postback is not a supported scenario.

You can optionally try implementing this behaviour with custom code.
The last checked item index can be stored in a HiddenField at OnClientItemChecked event handler function.
Then at OnClientDropDownOpened event you can “scroll” to this item explicitly.
<script type="text/javascript">
 
var hiddenField;
var indexToHighLight;
 
function pageLoad() {
    hiddenField = document.getElementById("<%=lastCheckedIndex.ClientID %>");
    indexToHighLight = hiddenField.value;
}
 
function OnClientDropDownOpening(sender, eventArgs) {
    var items = sender.get_items();
 
    if (indexToHighLight) {
        items.getItem(indexToHighLight).highlight();
        items.getItem(indexToHighLight).scrollOnTop();
    }
}
 
function OnClientItemChecked(sender, eventArgs) {
    hiddenField.value = eventArgs.get_item().get_index();
    indexToHighLight = eventArgs.get_item().get_index()
}
 
 
</script>


<telerik:RadComboBox ID="RadComboBox2" runat="server"
    OnClientDropDownOpened="OnClientDropDownOpening"
    OnClientItemChecked="OnClientItemChecked"
    AutoPostBack="true"
    CheckBoxes="true"
    EnableCheckAllItemsCheckBox="true"
    Height="70px">
    <Items>
        <telerik:RadComboBoxItem Text="test1" Value="1" />
        <telerik:RadComboBoxItem Text="test2" Value="2" />
        <telerik:RadComboBoxItem Text="test3" Value="3" />
        <telerik:RadComboBoxItem Text="test4" Value="4" />
        <telerik:RadComboBoxItem Text="test5" Value="5" />
        <telerik:RadComboBoxItem Text="test6" Value="6" />
        <telerik:RadComboBoxItem Text="test7" Value="7" />
        <telerik:RadComboBoxItem Text="test8" Value="8" />
        <telerik:RadComboBoxItem Text="test9" Value="9" />
        <telerik:RadComboBoxItem Text="test10" Value="10" />
        <telerik:RadComboBoxItem Text="test11" Value="11" />
    </Items>
</telerik:RadComboBox>
<asp:HiddenField ID="lastCheckedIndex" runat="server" />

All the best,
Kalina
the Telerik team
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Tracy
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answered on 22 Oct 2012, 07:04 PM
Hi Kalina,

This worked perfectly.

Thanks for your help.
Tracy
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Tracy
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