Last Updated: 20 Jun 2024 14:11 by Brian
Release 5.0.0 (15 Nov 2023) (R1 PI1)

I have a ComboBox/DropDownList that gets data from a remote service, using virtualization. When the PageSize property is big enough (in my case 20), I have issues scrolling up the selection box dropdown list. I'm trying to scroll but then resets to the currently selected item making it almost impossible to scroll up. You can use your own demo examples to replicate this issue.

To reproduce the issue, try the ComboBox - Virtualization, in Telerik REPL (Demo), change the PageSize from 10 to 20. Open the dropdown and select an item. Then, open again the dropdown and scroll slowly up.

Last Updated: 07 Jun 2024 18:57 by Jonathan
Created by: Alexander
Comments: 6
Category: ComboBox
Type: Bug Report

When the option "AllowCustom" is enabled for a TelerikComboBox and the user types something above a certain speed, typed characters are lost. Here is a GIF showing the problem on the page – I typed "123456", but end up with "1246" instead. In between the input field is showing some weird glitching.

Is there a way to have the TelerikComboBox behave normally, as it apparently did in versions prior to 4.3.0? We noticed this behavior only some time after upgrading from version 4.0.1, where everything still works properly.

Last Updated: 05 Mar 2024 12:10 by ADMIN

I am working on a form where experienced agents need to input data quickly. Often enough they know the codes and so they can type them in the combo box, but they shouldn't have to look for the mouse to select the item, the combo box should select it when the user presses Tab to move to the next field.

This should happen only when the user has filtered the combo box so they see some items (and so the dropdown is open) - I want them to be able to select only items from the available options, AllowCustom does not work for me.



Here is one workaround you can consider:

@inject IJSRuntime js

@* Move this script to a separate JS file *@
<script suppress-error="BL9992">
    function getHighligtedComboItem() {
        // Get the currently focused item in this particular ComboBox.
        var focusedItem = document.querySelector(".select-on-tab .k-list-item.k-focus");
        if (focusedItem) {
            return focusedItem.innerText;

<p>FirstFilteredItem: @FirstFilteredItem</p>

<p>Selected value: @ComboBoxValue</p>

<span onkeyup="@GetFirstFilteredItem">
    <TelerikComboBox Data="@ComboBoxData"
                     ValueChanged="@( (int newValue) => ComboBoxValueChanged(newValue) )"
                     OnOpen="@( () => IsComboBoxOpen = true )"
                     OnClose="@( () => IsComboBoxOpen = false )"
                     Placeholder="Select an item..."
            <ComboBoxPopupSettings Class="select-on-tab" />

<input placeholder="another form element" />

@code {
    private IEnumerable<ListItem> ComboBoxData = Enumerable.Range(1, 123).Select(x => new ListItem { Text = "Item " + x, Value = x });

    private int ComboBoxValue { get; set; }

    private string FirstFilteredItem { get; set; } = string.Empty;

    private bool IsComboBoxOpen { get; set; }

    private async Task GetFirstFilteredItem(KeyboardEventArgs args)
        if (!IsComboBoxOpen)
            // Wait at least 300ms, which is the opening animation.
            await Task.Delay(400);
            // Wait, depending on the typical filtering time.
            await Task.Delay(300);

        // The code that will find the item text depends on the exact scenario and potential use of ItemTemplate.
        FirstFilteredItem = await js.InvokeAsync<string>("getHighligtedComboItem");

    private void SelectItemOnTab()
        if (!string.IsNullOrEmpty(FirstFilteredItem))
            // Match the filter operation to the filter operator of the ComboBox.
            var matchingItem = ComboBoxData.Where(x => x.Text.ToLowerInvariant().Contains(FirstFilteredItem.Trim().ToLowerInvariant())).FirstOrDefault();
            if (matchingItem != null)
                ComboBoxValue = matchingItem.Value;
                FirstFilteredItem = string.Empty;

    private void ComboBoxValueChanged(int newValue)
        ComboBoxValue = newValue;
        FirstFilteredItem = string.Empty;

    public class ListItem
        public int Value { get; set; }
        public string Text { get; set; } = string.Empty;


Last Updated: 14 Feb 2024 13:13 by Bably

An open ComboBox will not close when the user tabs out of it when the ComboBox is the last component on the page. Here is a test example: Creating Blazor ComboBox

If there is another component after the ComboBo, then tabbing out works correctly.

Last Updated: 25 Dec 2023 13:27 by ADMIN
Release 5.1.0 (31 Jan 2024) (R1 2024)

The popup window is not closed when the ComboBox is disabled from code.

Reproduction code:


Selected value: @selectedValue
<br />

<TelerikComboBox Data="@myComboData"
                 ValueChanged="@((int value) => ValueChangedHandler(value))"
                 Placeholder="Select an item..."

@code {
    public bool isEnabled { get; set; } = true;
    IEnumerable<MyDdlModel> myComboData = Enumerable.Range(1, 20).Select(x => new MyDdlModel { MyTextField = "item " + x, MyValueField = x });

    int selectedValue { get; set; } = 3; //usually the current value should come from the model data

    public async Task ValueChangedHandler(int value)
        isEnabled = false;
        await Task.Delay(4000); //simulate network delay

        selectedValue = value;

        isEnabled = true;

    //in a real case, the model is usually in a separate file
    //the model type and value field type must be provided to the dropdpownlist
    public class MyDdlModel
        public int MyValueField { get; set; }
        public string MyTextField { get; set; }


Last Updated: 06 Nov 2023 16:56 by Miroslav


Steps to reproduce:

  1. Open popup.
  2. Use the keyboard to navigate to the first item.
  3. Type "1", so the input value is "item11" (a value that matches an item from the list) -> ValueChanged is not fired.
  4. Type "1" again, so the input value is "item111" (this is a custom value not present in the list) -> ValueChanged is fired.
  5. Delete the last "1", so the input value is again "item11"(a value that matches an item from the list) -> ValueChanged is not fired.
Last Updated: 31 Oct 2023 12:13 by ADMIN
Release 5.0.0 (15 Nov 2023) (R1 PI1)
When I enable the ReadOnly parameter, I can still tab into the input of the ComboBox and change the component value with the arrow keys.
Last Updated: 31 Oct 2023 07:36 by ADMIN
Release 5.0.0 (15 Nov 2023) (R1 PI1)
The extended DDL is reopened as soon as it is clicked to close it. The problem can be reproduced on Telerik's demo page. Blazor UI version 3.6.1 and 4.0.0 on Safari 15.6.1 and 16:
Last Updated: 11 Aug 2023 09:17 by ADMIN
Release 4.5.0 (08/30/2023) (R3 PI2)

When the height of the popup is set to 'auto' and it opens upwards, the resizing process causes it to be incorrectly positioned.

# Reproduction:

1. Open this REPL -
2. Shrink the browser so that the ComboBox remains at the bottom of the window: 

3. Type "item 2" in the ComboBox

Last Updated: 22 Jun 2023 09:23 by Ben

I'd like to report a bug with the Telerik combo box opening animation.

The problem can be reproduced on your page

Reproduction steps

1. Open page
2. Change the window to restored mode
3. Open the Product combo box and observe that the popup animation works as expected
4. Resize the window slightly vertically
5. Open the Product combo box
6. Observe that the combo box popup animation starts in the wrong place

This issue is 100% reproduceable every time and also can be reproduce if the popup is opened and the window is maximized.

Please see the attached video from about 15 to 25 seconds. Note that I reproduce the issue in the video a couple of times however due to the quality of it you can only see the incorrect animation between 15 to 25 seconds.

I hope the information helps.

Last Updated: 19 Jun 2023 08:02 by Peter
When the validation summary is placed and triggered above the Combobox component, it causes the combo input to move down hiding it behind the popup.
Last Updated: 07 Jun 2023 18:29 by Dialog
Created by: Dialog
Comments: 0
Category: ComboBox
Type: Feature Request

The tablet that I am using is slightly wider than the medium breakpoints set in AdaptiveMode.Auto. However, I still want to show the action sheet. I'd like to be able to configure the breakpoints which are currently hard-coded.




The request is opened for ComboBox but it also targets other selects and pickers that have AdaptiveMode feature. For example, DropDownList, MultiSelect, DatePicker and more.

Last Updated: 28 Mar 2023 14:49 by ADMIN
Release 4.2.0 (04/26/2023)

When selecting an item with the Enter key, the value is not displayed in the input field.

  1. Open this REPL example
  2. Open the ComboBox and navigate with the arrows to any item
  3. Hit "Enter" to select the item

The item is selected, but its value is not displayed inside the input field.


The issue is also reproducible with the MultiColumnComboBox component. 

Last Updated: 21 Mar 2023 12:11 by ADMIN


When selecting a value via the keyboard, the input element is out of sync.

Reproduction (if bug)

1. Create a Combobox and populate it with data.

2. Trigger a change with the keyboard.

3. The value is updated but the input holds the old value and is out of sync.

REPL for reproduction:

Last Updated: 10 Mar 2023 18:07 by Peter


 iam found "strange" behaviour compared to previous versions in combobox, with custom paging, filtering, valuemapper.

"simple description":
- Do not call OnRead and ValueMapper AFTER clicking/selecting the ITEM in any case(after filtering, or after scrolling...). Do it same way as selecting WITHOUT prior filtering.

Complex test

A sample for testing is here(and comments inside):

How to reproduce:

1 - start = value is PREselected - OK
2 - clear the combobox - OK
2 - input value 40  - slowly do not rush, number by number - OK
3- wait 2 seconds and Click/select item ("Name 401" etc) - NOK
observe the events fired(Exception/info: time - indicates that OnRead was fired again) 

Repeat the same WITHOUT filtering, just scrolling
observe the events fired = looks ok (Exception/info: time)

When selecting item by CLICKING on it(after filtering) looks like those events are fired:
- ValueMapper (why?)
- OnRead again(why again?)
- bind value (ok)
and sometimes ValueMapper again
it depends of "timing"

When selecting item by CLICKING on it:
- BIND the value. Everything is in there(no reason to call OnRead or ValueMapper)

Related, unexpected(video attachment):
Also when working in "real" scenario, AFTER clicking on item AFTER filtering, it returns full MODEL assembly path into to input filed, instead of clicked item
Lets have a list: {Name of the item,Another item,Next item}
entere in combobox/filter "name", results are shown ok, clicked on one and result shuld be ("Name of the item"), after clicking it returns "base model class name"
ie: "inwApp1.Pages.prozam.crm.EdcrmOrg+BaseKeyModel" - you dont want to see this :) .

There is different event orders for those 2 scenarios(it should be the same for both as at point 1) ):
1) when SELECTing item without filtering(just moving with scrollbar down to value 401 (only with onread and virtual paging)) = OK
2) when filtering by value "40" and SELECTing item by clicking on it - NOT OK = it look like this causes the problems and subsequent event calls

Is there any workaround, or new "property" to set? Thanks

Last Updated: 23 Jan 2023 09:08 by Stefan

When the user selects a value and then focuses on another component the OnBlur of the ComboBox is not triggered. The issue is reproducible in the Firefox browser (tested with version 109.0).

To reproduce the issue open the following REPL example in the Firefox browser:

Select a value in the first ComboBox and then focus on the second ComboBox. The OnBlur event should trigger.

Last Updated: 20 Jan 2023 08:18 by ADMIN
Release 4.1.0 (15/03/2023)
Created by: Niels Døssing
Comments: 1
Category: ComboBox
Type: Bug Report


EDIT: This issue (of course) relates to the case where the combobox has data selected when rendering.

The clear button of the combobox behaves in a way that I find strange, and which prevents us to get the desired behaviour in our application.

It is easily reproducable with your demo here:

When loading the page there is no clear button, which I think is wrong. Especially since it is not even in the DOM, so it cannot be made visible with styling. When clicking in the field, the clear button appears, and it stays there when changing focus to elsewhere, which seems inconsistent.

In other words, the span of the button (in the red box below) only appears when the combobox has had focus.



Last Updated: 18 Jan 2023 06:55 by ADMIN

I would like the ability to flag elements in a data bound combo that are no longer available as disabled and not selectable.  Had they been previously selected, they still need to show, but should not allow a user to select it again.

I would like a property that can be set when databinding a combo.

For instance when you set the Data, TextField, & ValueField properties, can there also be one for SelectableField (or something) - this could be mapped to a Boolean in the dataset.

If this property isn't used then it defaults to yes (ie they are all selectable), but if it is used, then any items which have this field set to 'no' then they show as a different color (could just be grey) but are not selectable by the user.

If they had previously been selected (prior to being marked as no longer available) then they should show when the record is loaded, but otherwise they are not selectable.

I don't particularly want to write code on click to see if its enabled and then unselect it, I would prefer it to simply be built into the base control.

Is this possible?  Or is there another property already there that does this?

Last Updated: 06 Dec 2022 09:39 by ADMIN
Release 4.0.0 (18 Jan 2023) (R1 2023)
Created by: Andrew
Comments: 2
Category: ComboBox
Type: Feature Request

I would like to change the text in the ComboBox dropdown when there is no data in the source collection.

At the moment the only option is through localization for all instances like here.

Last Updated: 25 Oct 2022 22:32 by ADMIN
Created by: Rick
Comments: 1
Category: ComboBox
Type: Feature Request

We are needing a way to display a hierarchy inside the ComboBox.  I don't see any examples on this particular feature, I had found a similar request, but not identical.

Our use case:

We have administrators that manage multiple tenants within our system.  The tenants are part of a hierarchy, the user needs to be able to select a tenant or tenant parent.

I will use hotels as an example:

-Chain 1

--Brand 1

---Property 1

---Property 2

--Brand 2

---Property 3

Our current system that we are migrating controls from has this feature, so I would like to stick as close to this functionality as possible, however; if it is not an option, what control would you suggest as an alternative.

See example (sorry for the redactions)

The core concept is providing a user a choice as part of a form, but layout needs to be organized so that a user can easily navigate.  Top level names are unique, all other names can duplicate since they may share similar naming conventions across different organizations.

An option that may work as an alternative, is invoking a dialog popup and within it having a tree list of the information I need.  I think it could work, but it would certainly break the flow of the form.

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