Hi Support,

I have an issue with the DragToSelect feature of a Telerik grid in Blazor when this grid is inside a TelerikWindow. 

Summary
When a TelerikGrid configured with GridSelectionSettings DragToSelect="true" is rendered inside the <WindowContent> of a <TelerikWindow>, the drag-to-select (rubber-band) behavior is not working properly — the user can only select cells/rows via individual clicks.

Single-click selection continues to work in both cases. The issue is specific to the drag gesture.

Steps to reproduce
Create a page with a TelerikWindow set to Visible="true".
Inside <WindowContent>, place a TelerikGrid with:
SelectionMode="@GridSelectionMode.Multiple"
SelectedCells / SelectedCellsChanged bound
<GridSettings><GridSelectionSettings SelectionType="@GridSelectionType.Cell" DragToSelect="true" /></GridSettings>
Open the window and try to select multiple cells by pressing the mouse button on a cell and dragging over neighboring cells.

Expected behavior
A rubber-band selection rectangle appears and all cells the pointer passes over become selected — same as when the identical grid is placed on a regular page (outside a modal window).

Actual behavior
Drag selection occur rarely. Only the single cell under the initial mousedown gets selected. The rubber-band rectangle rarely appears, and SelectedCellsChanged fires with a single descriptor instead of the full drag range.

Minimal repro (REPL-ready)
<TelerikWindow Visible="true" Width="800px" Height="500px">
    <WindowTitle>Repro</WindowTitle>
    <WindowContent>
        <TelerikGrid Data="@Data" TItem="SampleItem"
                     SelectionMode="@GridSelectionMode.Multiple"
                     SelectedCells="@SelectedCells"
                     SelectedCellsChanged="@((IEnumerable<GridSelectedCellDescriptor> c) => SelectedCells = c)">
            <GridSettings>
                <GridSelectionSettings SelectionType="@GridSelectionType.Cell" DragToSelect="true" />
            </GridSettings>
            <GridColumns>
                <GridColumn Field="@nameof(SampleItem.Id)" />
                <GridColumn Field="@nameof(SampleItem.Name)" />
            </GridColumns>
        </TelerikGrid>
    </WindowContent>
</TelerikWindow>

@code {
    public record SampleItem(int Id, string Name);
    private List<SampleItem> Data = Enumerable.Range(1, 20).Select(i => new SampleItem(i, $"Item {i}")).ToList();
    private IEnumerable<GridSelectedCellDescriptor> SelectedCells = Enumerable.Empty<GridSelectedCellDescriptor>();
}

Now my questions :
- Is this a known limitation of DragToSelect when the grid is inside a modal TelerikWindow?
- Is there an officially supported workaround (CSS pointer-events tweak on .k-overlay, event capture override, grid setting, etc.)?
- If it is a bug, could you open a public issue we can track?

Many thanks you in advance.

Franck Boisdé

Bug report

Reproduction of the problem

Possibly related to https://github.com/telerik/blazor/issues/2594

1. Run this example: https://blazorrepl.telerik.com/wAkdbZPo47oCuV5G32
2. Without scrolling the Grid horizontally resize a non-locked column (e.g., In Stock)

Current behavior

(optional)

The first locked column (ID) is rendered after the second locked column (Product Name). When you resize a non-locked column, the ID column disappears and is revealed at its new position after you scroll the Grid horizontally.
The behavior is reproducible with RTL enabled.

Expected/desired behavior

The order of the locked columns should persist.

Environment

• Telerik version: 13.0.0
• Browser: [all]

Telerik input components inside EditorTemplate render the whole grid on each keystroke

<AdminEdit>

As a workaround, you can use the standard Input components provided by the framework together with a CSS class that would visually make them like the Telerik Input Components. An example for the TextArea:

<InputTextArea class="k-textarea" @bind-Value="@myValue"></InputTextArea>

</AdminEdit>

The Grid performance worsens progressively with each subsequent edit operation. Please optimize that.

Test page: https://blazorrepl.telerik.com/mJuHFNbb17FpJu9b54

Click on a Price or Quantity cell to start edit mode and tab repetitively to observe the degradation.

Bug Description

Introduced in v13.1.0. An item that has no text (empty string) renders a span (.k-list-item-text) with height 0px.

Steps to Reproduce

Steps to reproduce the behavior:

1. Go to https://blazorrepl.telerik.com/mgEobKlm00OJm8OW55
2. Click the DropDownList to show its list
3. Inspect the second item in the browser dev tools

Also reproducible in: https://dojo.telerik.com/ZVOXYUsb/3

Expected Behavior

The item that has no text should have the same height as items that have text.

Actual Behavior

The height of the span.k-list-item-text is 0px.

Screenshots/Videos

Environment Information

Affected Theme(s)

• All themes

Affected Component(s)

Please specify the component(s) where the bug occurs: ___________

Affected Suites

• Kendo UI for jQuery
• Telerik UI for Blazor
• Telerik UI for ASP.NET Core
• Telerik UI for ASP.NET MVC
• likely others as well

Browser Information

• All browsers

Build System Information

Reproduction Case

CodePen/StackBlitz/JSFiddle Link

https://blazorrepl.telerik.com/mgEobKlm00OJm8OW55

https://dojo.telerik.com/ZVOXYUsb/3

Sample Code

<TelerikDropDownList Data="@DropDownListData" @bind-Value="DropDownListValue" />

@code {
    private List<string> DropDownListData = new List<string>() { "Item1", string.Empty, "Item3" };

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

    protected override void OnInitialized()
    {
        DropDownListValue = string.Empty;
    }
}

Workaround

<style>
    .k-list-item-text {
        min-height: 20px;
    }
</style>

OnChange and OnBlur event for editors (TelerikTextBox, NumericTextBox, and others) is not fired in InCell edit mode with Tab key.

Hi,

The ask is for a feature request to take the already wonderfully done globally applied filter features down to a per column basis without the overhead and burden of resorting to the custom FilterMenuTemplate approach.

The current way of doing business creates much overhead in code particularly when several columns are involved.

Something like:

<TelerikGrid Data="@MyData"
FilterMode="@GridFilterMode.PerColumn"

<GridColumns>
<GridColumn Field="MyField01" FilterMode="@GridFilterColumnMode.FilterRow" />

<GridColumn Field="MyField02" FilterMode="@GridFilterColumnMode.FilterMenu" />

<GridColumn Field="MyField03" Filterable="false"/>

etc..

</GridColumns>

</TelerikGrid>

Thanks!

Ron

How to reproduce:

1. Go to https://demos.telerik.com/blazor-ui/grid/editing-incell
2. Go to the last Grid page, which has empty space below the last table row.
3. Open any Grid cell for editing.
4. Click on the empty space in the Grid below the last table row.
5. The Grid does not exit edit mode like it should.

The regression was introduced in version 12.2.0. The last version that works correctly is 12.0.0.

The possible workarounds are:

• Remove the Grid Height, so that there is no empty space after the last Grid row. You can apply a max-height style to the Grid to prevent unlimited vertical expansion.
• Use an @onfocusout event in the Grid <EditorTemplate> to close the Grid edit mode programmatically:

@using System.ComponentModel.DataAnnotations
@using Telerik.DataSource
@using Telerik.DataSource.Extensions

<TelerikGrid @ref="@GridRef"
             OnRead="@OnGridRead"
             TItem="@Product"
             EditMode="@GridEditMode.Incell"
             OnCreate="@OnGridCreate"
             OnDelete="@OnGridDelete"
             OnUpdate="@OnGridUpdate"
             Height="600px">
    <GridToolBarTemplate>
        <GridCommandButton Command="Add">Add Item</GridCommandButton>
    </GridToolBarTemplate>
    <GridColumns>
        <GridColumn Field="@nameof(Product.Name)">
            <EditorTemplate>
                @{ var dataItem = (Product)context; }
                <span @onfocusout="@( async () => await OnGridCellFocusOut(nameof(Product.Name)) )">
                    <TelerikTextBox @bind-Value="@dataItem.Name" />
                </span>
            </EditorTemplate>
        </GridColumn>
        @* <GridColumn Field="@nameof(Product.Price)" DisplayFormat="{0:C2}" />
        <GridColumn Field="@nameof(Product.Quantity)" DisplayFormat="{0:N0}" />
        <GridColumn Field="@nameof(Product.ReleaseDate)" DisplayFormat="{0:d}" /> *@
        <GridColumn Field="@nameof(Product.Discontinued)" Width="120px">
            <EditorTemplate>
                @{ var dataItem = (Product)context; }
                <span @onfocusout="@( async () => await OnGridCellFocusOut(nameof(Product.Discontinued)) )">
                    <TelerikCheckBox @bind-Value="@dataItem.Discontinued" />
                </span>
            </EditorTemplate>
        </GridColumn>
        <GridCommandColumn Width="180px">
            <GridCommandButton Command="Delete">Delete</GridCommandButton>
        </GridCommandColumn>
    </GridColumns>
</TelerikGrid>

@code {
    private TelerikGrid<Product>? GridRef { get; set; }

    private ProductService GridProductService { get; set; } = new();

    private async Task OnGridCellFocusOut(string field)
    {
        await Task.Delay(100);

        if (GridRef is null)
        {
            return;
        }

        GridState<Product> gridState = GridRef.GetState();
        Product? editItem = gridState.EditItem as Product;

        if (editItem is null)
        {
            return;
        }

        GridCommandEventArgs args = new GridCommandEventArgs()
        {
             Field = field,
             Item = editItem
        };

        await OnGridUpdate(args);


        gridState.EditField = default;
        gridState.EditItem = default!;
        gridState.OriginalEditItem = default!;

        await GridRef.SetStateAsync(gridState);
    }

    private async Task OnGridCreate(GridCommandEventArgs args)
    {
        var createdItem = (Product)args.Item;

        await GridProductService.Create(createdItem);
    }

    private async Task OnGridDelete(GridCommandEventArgs args)
    {
        var deletedItem = (Product)args.Item;

        await GridProductService.Delete(deletedItem);
    }

    private async Task OnGridRead(GridReadEventArgs args)
    {
        DataSourceResult result = await GridProductService.Read(args.Request);

        args.Data = result.Data;
        args.Total = result.Total;
        args.AggregateResults = result.AggregateResults;
    }

    private async Task OnGridUpdate(GridCommandEventArgs args)
    {
        var updatedItem = (Product)args.Item;

        await GridProductService.Update(updatedItem);
    }

    public class Product
    {
        public int Id { get; set; }
        [Required]
        public string Name { get; set; } = string.Empty;
        public string Description { get; set; } = string.Empty;
        public decimal? Price { get; set; }
        public int Quantity { get; set; }
        [Required]
        public DateTime? ReleaseDate { get; set; }
        public bool Discontinued { get; set; }
    }

    #region Data Service

    public class ProductService
    {
        private List<Product> Items { get; set; } = new();

        private int LastId { get; set; }

        public async Task<int> Create(Product product)
        {
            await SimulateAsyncOperation();

            product.Id = ++LastId;

            Items.Insert(0, product);

            return LastId;
        }

        public async Task<bool> Delete(Product product)
        {
            await SimulateAsyncOperation();

            if (Items.Contains(product))
            {
                Items.Remove(product);

                return true;
            }

            return false;
        }

        public async Task<List<Product>> Read()
        {
            await SimulateAsyncOperation();

            return Items;
        }

        public async Task<DataSourceResult> Read(DataSourceRequest request)
        {
            return await Items.ToDataSourceResultAsync(request);
        }

        public async Task<bool> Update(Product product)
        {
            await SimulateAsyncOperation();

            int originalItemIndex = Items.FindIndex(x => x.Id == product.Id);

            if (originalItemIndex != -1)
            {
                Items[originalItemIndex] = product;
                return true;
            }

            return false;
        }

        private async Task SimulateAsyncOperation()
        {
            await Task.Delay(100);
        }

        public ProductService(int itemCount = 5)
        {
            Random rnd = Random.Shared;

            for (int i = 1; i <= itemCount; i++)
            {
                Items.Add(new Product()
                {
                    Id = ++LastId,
                    Name = $"Product {LastId}",
                    Description = $"Multi-line\ndescription {LastId}",
                    Price = LastId % 2 == 0 ? null : rnd.Next(0, 100) * 1.23m,
                    Quantity = LastId % 2 == 0 ? 0 : rnd.Next(0, 3000),
                    ReleaseDate = DateTime.Today.AddDays(-rnd.Next(365, 3650)),
                    Discontinued = LastId % 2 == 0
                });
            }
        }
    }

    #endregion Data Service
}

In a filterable Grid, if a column is not bound to a field from the model the Grid uses, it throws with:

Error: System.ArgumentNullException: Value cannot be null. (Parameter 'nullableType')

Reproduction: https://blazorrepl.telerik.com/GyEUlFEs04AUJoJ601.

The issue is reproducible :

• For `FilterRow` -  on initialization even if the column is not filterable.
• For `FilterMenu` - on initialization when the column is filterable.

===

ADMIN EDIT

===

A possible workaround for the time being is to set the FieldType of the column: https://blazorrepl.telerik.com/wSugvFui10jhcpZy00.

I am resetting the Grid State by calling Grid.SetState(null). This doesn't reset ColumnState<T>.Locked boolean to false and the columns remain locked.

---

ADMIN EDIT

---

A possible workaround for the time being is to additionally loop through the ColumnStates collection of the State and set the Locked property to false for each column.

Example: https://blazorrepl.telerik.com/QTYmkpvb49c6CPxa42

If LoadGroupsOnDemand="false", I am able to programmatically expand the groups through the state. However, this is not possible when loading group data on demand.

Please allow programmatically expanding the groups when LoadGroupsOnDemand="true". This should go together with an event (OnStateChanged?) that will fire when LOD groups are expanded or collapsed.

Draft feature request (copy/paste)

Title: Add per-column value converters (WPF-style) to Telerik Blazor Grid columns

Product: UI for Blazor → Grid
Type: Feature Request

Description:
In Telerik UI for WPF, grid column definitions can reference a converter by name (e.g., IValueConverter) to transform values for display without writing a custom cell template for each column.

In Telerik UI for Blazor Grid, templates are currently the primary way to change how values render in a column (which works, but becomes repetitive across many columns/grids).

Request:
Add a column-level conversion API that allows specifying a converter/formatter function for display (and optionally editing). Example concepts:

• Converter="nameof(MyConverters.StatusToText)"

• or DisplayConverter="(item) => …" / ValueFormatter="Func<TItem, object, string>"

• optionally ConvertBack-like support for editing scenarios (or separate EditConverter)

Why this is needed:

• Reduces repeated <Template> markup for simple formatting/transformations

• Centralizes formatting/conversion logic in reusable code

• Improves maintainability and consistency across grids

• Eases migration for teams coming from Telerik WPF where converters are a common pattern

Use cases:

• Enum/int → user-friendly text

• Boolean → “Yes/No”, icons, badges

• Null/empty → placeholder text

• Code → display name (via lookup)

• Domain-specific formatting shared across many grids

Workarounds today:

• Column <Template> or computed properties (both valid, but not as concise/reusable for large grids)

• Extracting RenderFragments can reduce repetition, but still requires templating infrastructure for what is logically a simple conversion step

Expected behavior:

• Converter applies consistently anywhere the column renders (cell, export if applicable, etc.)

• Works with sorting/filtering in a predictable way (ideally sorting/filtering still uses raw field value unless explicitly configured)

Hello,

seems like the GridToolbar(even the GridToolbarTemplate) in grid is not rendering "GridToolBarOverflowMode.Section". The "Scroll" mode is ok.

Is there any additional setup, or did i missed some setup...?

REPL:

 https://blazorrepl.telerik.com/wqYQvvEq40GkajEZ30

based on:
https://www.telerik.com/blazor-ui/documentation/components/grid/toolbar

some mention about "sections" but it seems for another purpose:

https://www.telerik.com/blazor-ui/documentation/knowledge-base/common-net8-sections

Thanks