There are missing methods in the TypeScript definitions provided. 

You can find attached a file that illustrates what needs to be updated.

A workaround is to remove the loading sign functionality by placing the following script at the end of the form tag

The second override is necessary only if you use the OnClientDataLoaded event to alter the data and add fields in the data object that do not exist in the server response. You need to rename the OnClientDataLoaded method call to use your actual method name.

You can find an example of both workarounds and their usage attached.

Some additional information:
- If possible, move the tiles out of the AJAX request, as this will eliminate all of the problems. Depending on the actual scenario perhaps you can make sure they are not in an update panel (e.g., position them absolutely on the page while keeping their markup out of the partial postback).
- consider moving any data formatting logic from the event handler to the template. You can define functions that format the code in the template, not only in the event. An example is available in the attached file. Alternatively, you can return the data formatted from the web service.
- consider reducing the time interval for the requests, because after the AJAX request, only 1 of 2 requests will update the tile UI.

In lightweight the issue is not observed:

<telerik:RadRibbonBar runat="server" RenderMode="Classic">
    <Tabs>
        <telerik:RibbonBarTab Text="home">
            <%-- duplicate the group and items inside to replicate more easily --%>
            <telerik:RibbonBarGroup Text="Documents">
                <Items>
                    <telerik:RibbonBarButton Text="Item 1" />
                </Items>
            </telerik:RibbonBarGroup>
        </telerik:RibbonBarTab>
    </Tabs>
</telerik:RadRibbonBar>

The Delete and Backspace buttons remain enabled in spell check mode, allowing the client to delete selections inside the Editor's content area.

Steps to reproduce:
1. Open http://demos.telerik.com/aspnet-ajax/editor/examples/spellchecker/defaultcs.aspx
2. Click the Spell check icon
3. Select several words from the content and press Backspace/Delete

Result: The selected content is deleted
Expected: The Delete/Backspace button press is ignored

OnClientModeChange event is not fired in Mobile RenderMode.

Steps to reproduce:
Run the following code in a mobile Chrome (or mobile emulation) and click the edit Pencil button that switches the edit modes:

        <script type="text/javascript">
            function OnClientModeChange(editor, args) {
                var mode = editor.get_mode();
                switch (mode) {
                    case 1:
                        alert("We are in Design mode");
                        //do something
                        break;
                    case 2:
                        alert("We are in Html mode");
                        //do something
                        break;
                    case 4:
                        alert("We are in Preview mode");
                        //do something
                        break;
                }
            }
        </script>

        <telerik:RadEditor runat="server" OnClientModeChange="OnClientModeChange" ID="RadEditor1" RenderMode="Auto">
        </telerik:RadEditor>

Images with "*.jpeg" extension are saved as "*.jpg" in a different file even if the "Overwrite" option is checked. 

Steps to reproduce:

When tabbing from first PanelBar to the second one it neither passes through the contentTemplate elements, nor to the second panelbar:
 
<telerik:RadPanelBar runat="server" ID="radPnlBarFundingSources" Width="100%" ExpandMode="MultipleExpandedItems" TabIndex="1">
            <Items>
                <telerik:RadPanelItem runat="server" Text="Funding Source">
                    <ContentTemplate>
                        <telerik:RadListBox runat="server" ID="radLbAvailFundingSource" Height="100px" Width="40%" SelectionMode="Multiple" AllowTransfer="true" TransferMode="Move" AllowTransferOnDoubleClick="true" TransferToID="radLbSelFundingSource" ButtonSettings-AreaWidth="35px" Enabled="True" style="font-family: Verdana, Trebuchet MS,Arial,sans-serif; font-size:0.9em;"></telerik:RadListBox>
                        <telerik:RadListBox runat="server" ID="radLbSelFundingSource" Height="100px" Width="40%"></telerik:RadListBox>
                    </ContentTemplate>
                </telerik:RadPanelItem>
            </Items>
        </telerik:RadPanelBar>
    </div>
    <div class="Row">
        <telerik:RadPanelBar runat="server" ID="radPnlBarContracts" Width="100%" TabIndex="2">
            <Items>
                 <telerik:RadPanelItem runat="server" Text="Contract">
                    <ContentTemplate>
                        <telerik:RadListBox runat="server" ID="radLbAvailContract" Height="100px" Width="40%" SelectionMode="Multiple" AllowTransfer="true" AllowTransferOnDoubleClick="true" TransferToID="radLbSelContract"  AutButtonSettings-AreaWidth="35px"></telerik:RadListBox>
                        <telerik:RadListBox runat="server" ID="radLbSelContract" Height="100px" Width="40%"></telerik:RadListBox>
                    </ContentTemplate>
                 </telerik:RadPanelItem>
            </Items>
        </telerik:RadPanelBar>

A property to handle that would be very convenient. This way developers could be able to restrict the number of rows that the user can type. Something like MaxRowNumber.

Additionally, a property MaxColumnNumber would be also useful to restrict the length of each row. 

The Bold, Italic, Underline, Justify, Indent, Outdent and other commands are not localized in the Undo/Redo dropdowns.

Screenshots:




Can be seen at http://demos.telerik.com/aspnet-ajax/editor/examples/localization/defaultcs.aspx. 

Hi!

I use .resx file to change Gantt labels with italian translation.

Everything works as expected with the exception of the assign resources button in advanced form (see attachment).

I tried to set declaratively with the Localization-AdvancedAssignResources property but it doesn't work.

Thanks in advance.

Mattia

Context / scenario

We run a large ASP.NET AJAX application with a fully custom, self-maintained CSS theme — we do not use any of Telerik's built-in skins. For this kind of setup we need complete control over every stylesheet that gets loaded into the page, both for consistency of our design system and to avoid unexpected CSS side effects or class-name collisions with resources we don't manage.

Issue

We found that fonticons.css is automatically and unconditionally injected by the Lightweight rendering path used by the controls (e.g. RadButton, RadTextBox, and other controls using the Lightweight render mode). This injection happens regardless of the EnableEmbeddedSkins and EnableEmbeddedBaseStylesheet settings, which normally let developers opt out of Telerik's embedded/base CSS resources. In other words, even with both of those settings disabled and no skin applied, fonticons.css is still loaded — there is currently no supported way to prevent it.

We raised this with Telerik support and it was confirmed internally: the fonticons.css injection is currently hard-wired into the Lightweight rendering path and is not gated by any existing configuration option.

Why this matters

• It breaks the expectation that EnableEmbeddedSkins / EnableEmbeddedBaseStylesheet = "nothing gets injected automatically" for teams running a fully custom theme.
• It adds an extra, unaccounted-for HTTP resource / set of CSS rules (font-face declarations and generic icon base classes) that our theme did not ask for and cannot easily audit or version alongside the rest of our stylesheet.
• Teams with strict content-security / asset-inventory requirements (e.g. wanting every loaded CSS file to be explicitly declared and controlled) currently have no clean way to achieve that with Telerik controls in Lightweight mode.
• The only current workaround (intercepting or modifying Telerik's internal resource registration) is explicitly discouraged by Telerik support itself, since that internal logic can change between versions and is not a supported extension point.

Feature request

Introduce a supported opt-out for the automatic fonticons.css injection in the Lightweight rendering path — for example, a new setting such as EnableFontIcons (page/control or global web.config level, consistent with how EnableEmbeddedSkins / EnableEmbeddedBaseStylesheet are already exposed) that lets developers explicitly disable this injection when they provide their own icon/font handling.

We understand from Telerik support that this is not a small, isolated change — it requires auditing and refactoring how style resources are declared and loaded across the whole control set (including some legacy resource-registration code) before a dedicated opt-out setting can be safely introduced, and that this carries a real risk of regressions if rushed. We're not expecting a quick fix; we're submitting this as a tracked feature request, as recommended by Telerik support, so it can be prioritized and voted on by other customers with the same fully-custom-theme use case.

Suggested acceptance criteria

• A documented way (config setting and/or API) to disable automatic fonticons.css injection specifically in Lightweight rendering mode.
• Behavior consistent with EnableEmbeddedSkins / EnableEmbeddedBaseStylesheet: when disabled, no font-icon CSS is emitted by the framework, leaving the developer fully responsible for providing equivalent styles if needed.
• No behavior change for existing applications that don't set the new opt-out (backward compatible by default).

When AutoSize is enabled on a RadWindow, the calculated width and height of the window can be larger than the actual content requires. The extra size appears as dead space around the content, on the right side for width and at the bottom for height, and is most noticeable when the content or its wrapping container has its own padding or border.

Steps to reproduce:

• Add a RadWindow with AutoSize="true" (any AutoSizeBehaviors).
  
• Set the window content either through a ContentTemplate with inline markup (for example a RadAjaxPanel), or through NavigateUrl pointing to a separate page.
  
• Give the content, or its wrapping container, a horizontal and/or vertical padding or border via CSS.
  
• Open the RadWindow and let it auto-size.
  

Result:
The RadWindow is wider and/or taller than necessary. The extra space is not evenly distributed and shows up as unexpected empty space next to or below the content.

Expected:
The RadWindow width and height should match the actual content size, with the same behavior as before the 2026 Q1 release.

The built-in commands in the RadSpreadsheet context menu does not execute. Commands such as Delete Row, Delete Column, Hide Row, and Unhide Row/Column appear in the context menu, but clicking them has no effect.

The issue is reproducible in the official demo site.

Steps to reproduce

1. Open a page containing a RadSpreadsheet control.
   
2. Right-click a row or column header.
   
3. Select a built-in command such as Delete, Hide, or Unhide.
   
4. Observe the spreadsheet.
   

Actual result
The menu closes, but the selected built-in command is not executed.

Expected result
The selected command should execute and update the spreadsheet, for example, deleting the selected row or column or changing its visibility.

If both the CSRF validation and the Session state is turned off, the pages containing AsyncUpload control will throw a null reference exception.

<appSettings>
  <add key="Telerik.AsyncUpload.EnableCsrfValidation" value="false" />
</appSettings>
<system.web>
  <sessionState mode="Off" />

Summary When a RadPane has Scrolling="Y" (or X/Both) and also has BorderWidth, BorderStyle, BorderColor set (either directly on the pane or via the parent RadSplitter's PanesBorderSize), the pane's inner scrollbar does not render/work correctly. The space reserved for the scrollbar remains in the layout, but the scrollbar itself is missing or non-functional, effectively making the pane's content unscrollable.

Steps to Reproduce

1. Create a RadSplitter with a RadPane that has Scrolling="Y" and BorderWidth="3" BorderStyle="solid" BorderColor="blue" (or just rely on PanesBorderSize).
2. Add enough content to the pane so it overflows vertically.
3. Load the page in Chrome (reproduced on Chrome 152).
4. Observe: only the outer document scrollbar appears; the pane's own scrollbar is missing or the reserved scrollbar gutter space is empty, and the content cannot be scrolled within the pane.

Expected behavior The pane's scrollbar should render correctly and remain functional regardless of BorderWidth/BorderStyle/BorderColor/PanesBorderSize settings.

Actual behavior Scrollbar space is reserved but the scrollbar is missing/non-functional when a border is applied to the pane.

------------------- AI Summary -------------------

We upgraded Telerik UI for ASP.NET AJAX from version 2026.2.708 to 2026.3.812, with no changes to our navigation menu code. Our RadPanelBar menu is populated server-side via DataBind() using a SiteMapDataSource (no client-side population). Since the upgrade, clicking a menu item frequently does not navigate to its URL: the menu shifts vertically, the clicked item is not selected, and no navigation occurs. This is impacting customers’ ability to use our site.

--------------- End of AI Summary ---------------

We are requesting assistance to troubleshoot and resolve this issue as quickly as possible. This problem is causing significant usability issues.