Unplanned
Last Updated: 27 Aug 2026 16:33 by Martin Ivanov
When RadRibbonView is minimized (IsMinimized="True") and KeyTips keyboard navigation is used to select a tab via ENTER or SPACE instead of typing an access-key letter, the ribbon's minimized popup opens over the window content as expected, but afterwards neither ESC nor ALT collapses it again. The popup remains open and overlaying the window content until the user clicks elsewhere with the mouse, trapping keyboard-only users in an invalid UI state.
Completed
Last Updated: 26 Aug 2026 12:27 by ADMIN
Release 2026.3.826 (2026 Q3)
LocalizableException with text "Format string is not in the correct format.", with inner ArgumentException "Format string is not in the correct format." is thrown. 

Currently the validation doesn't allow number format string starting with date or time formatting to have more that one section (for negative and zero numbers). Excel allows this type of number formats and if you set format like dd/mm/yyyy;[RED](#.##0); the positive numbers are visualized as dates, but negative numbers are visualized as numbers and their fore color is red.

Examples (including the final semicolons):

- ss;

- dd;

- dd/mm/yyyy;;

- mmm-yy;mmm-yy;_-* "-"??_-;_-@_-
Completed
Last Updated: 26 Aug 2026 12:27 by ADMIN
Release 2026.3.826 (2026 Q3)

Observed when loading a document: 

Completed
Last Updated: 26 Aug 2026 12:27 by ADMIN
Release 2026.3.826 (2026 Q3)
When number format ends with N commas, the resulting number should be divided to 1000 N times. Instead, such commas are ignored. 

For example, if the format is #.0,, and the value of the cell is 12,200,000, the number should be displayed as 12.200.0
Unplanned
Last Updated: 26 Aug 2026 08:59 by ADMIN
In this scenario, the RadRichTextBox is placed inside a RadTabControl. When switching between tabs and returning to the tab containing RadRichTextBox, we can no longer type in the control.
Unplanned
Last Updated: 24 Aug 2026 12:04 by ADMIN

ArgumentException: WebView2 was already initialized with a different CoreWebView2Environment. Check to see if the Source property was already set or EnsureCoreWebView2Async was previously called with different values.

at Microsoft.Web.WebView2.Wpf.WebView2Base.EnsureCoreWebView2Async(CoreWebView2Environment environment, CoreWebView2ControllerOptions controllerOptions)

Unplanned
Last Updated: 20 Aug 2026 09:01 by ADMIN
Unplanned
Last Updated: 19 Aug 2026 09:26 by Martin Ivanov

The keyboard arrow selection doesn't select tabs, just moves the focus. This happens when the content area of RadRibbonView is minimizable and open. 

To work this around, manually select the focused tab on key down.

private void RadRibbonView_PreviewKeyDown(object sender, KeyEventArgs e)
{
    var ribbon = (RadRibbonView)sender;
    if (ribbon.IsMinimized && (e.Key == Key.Left || e.Key == Key.Right))
    {
        var focusedHeader = Keyboard.FocusedElement as RadRibbonTab;
        if (focusedHeader != null && ribbon.SelectedItem != focusedHeader)
        {
            ribbon.SelectedItem = focusedHeader;
            e.Handled = false;
        }
    }
}

Declined
Last Updated: 19 Aug 2026 08:08 by ADMIN
Initially RibbonView gets rendered design-time. Trying to edit RibbonTab-s or add new one causes the whole control to dissapear in the designer. Clean and rebuild of the solution doesn't help -- cleaning the Shadow cache of Visual Studio Designer is the onliest thing that helps.

The issue reproduces with Class Library containing the Ribbon setup and IsWindowsThemeEnabled property of RibbonWIndow turned off (default value).
Unplanned
Last Updated: 18 Aug 2026 10:42 by ADMIN
Created by: Vladimir
Comments: 1
Category: AI Coding Assistant
Type: Feature Request
1
Provide a way to use the Telerik WPF MCP server in an air-gapped environment.
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
Currently, when the user is editing a cell and saves the document without leaving the edit mode first, the current value is not preserved in the saved document.
When pressing the File -> Save button in the ribbon, the Save dialog doesn't appear at all.
 
Workaround: Manually commit the change before saving. This workaround will also respect data validation:
var layer = ((NormalWorksheetEditorPresenter)radSpreadsheet.ActiveWorksheetEditor.ActivePresenter).UILayers.GetByName(WorksheetPredefinedUILayers.CellInput);
CellInputUILayer cellInputUILayer = (CellInputUILayer)layer;
cellInputUILayer.ApplyChange();
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
Value of a cell is visualized outside of the cell boundaries, or the value is clipped and partially visible, when the cell is updated (from code-behind), while being in an inactive worksheet, and is referenced by another cell from the active sheet.

Workaround: get a value of some cell in the active sheet and set it again to the same cell.

The issue is reproducible after the official release of Q1 2015.
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
When RadSpreadsheet is placed inside a data template and the Workbook property is bound, the binding fails. 

In the Convert() method of the debug converter, the proper value is set. However, an empty workbook is displayed in the view.
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
If the document contains a simple field without run inside, the import process fails. 

      <w:fldSimple w:instr="page" w:dirty="true"/>

The same document with a run inside the field does not cause an error

      <w:fldSimple w:instr="page" w:dirty="true">
        <w:r>
          <w:t>1</w:t>
        </w:r>
      </w:fldSimple>
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
Keyboard commands are not working for controls inside the InlineUIContainer. The reason for this is that RichTextBox is handling them.
The commands are: Left, Right, Backspace, Delete, Tab, Ctrl+C, Ctrl+V among others.

Workaround:
Attach custom event handler to the PreviewEditorKeyDown event of the RichTextBox. This event should set "e.SuppressDefaultAction = true" when the focus is in the InineUIContainer.
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
The label text is automatically fetched from the property name or manually set via the DisplayName property of the PropertyDefinition object. Currently, the property name is displayed in a TextBlock control. Add a mechanism to allow changing the label UI. For example, by providing a DataTemplate via a property of RadPropertyGrid or of the PropertyDefinition. 
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)

When a DropDownList SDT form is saved in a XAML document and then imported with the XamlFormatProvider, an extra ListItem entry is added in the items collection of the DropDownList. The extra entry is the default "Choose an item".

To work this around, iterate all ComboBoxProperties and manually remove duplicates of the "Choose an item" entry.

var dropDownLists = radRichTextBox.Document.EnumerateChildrenOfType<SdtRangeStart>()
     .Where(x => x.SdtProperties is ComboBoxProperties)
     .Select(x => x.SdtProperties).OfType<ComboBoxProperties>();
 var defaultItemString = LocalizationManager.GetString("Documents_ContentControlsGenerator_ListItem");
 foreach (var item in dropDownLists)
 {
     if (item.Items.Count > 0 && item.Items.Any(x => x.Value != defaultItemString) && item.Items.Any(x => x.Value == defaultItemString))
     {
         var occurrence = item.Items.FirstOrDefault(x => x.Value == defaultItemString);
         while (occurrence != null)
         {
             item.Items.Remove(occurrence);
             occurrence = item.Items.FirstOrDefault(x => x.Value == defaultItemString);
         }
     }
 }

Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)

For the German language translations, the following resource keys are translated into Dutch instead:

  • Spreadsheet_PrintPreview_FitSheetOnOnePage
  • Spreadsheet_PrintPreview_FitSheetOnOnePage_Description
  • Spreadsheet_PrintPreview_FitColumnsOnOnePage
  • Spreadsheet_PrintPreview_FitColumnsOnOnePage_Description
  • Spreadsheet_PrintPreview_FitRowsOnOnePage
  • Spreadsheet_PrintPreview_FitRowsOnOnePage_Description
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
A degraded performance is observed when the control is used in an application published with ClickOnce deployment. 
Completed
Last Updated: 13 Aug 2026 09:40 by ADMIN
Release Telerik UI for WPF 2026.3.812 (Q3 2026)
The DialogClosed event of RadFilePathPicker stops working when the DialogType property is changed.
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