Excel-like pop-up location is not scaled properly on High DPI.

The following error occurs when closing Property Builder at design time:

Use attached to reproduce.

Workaround: 
The vsdiffmerge.exe merge tool in Visual Studio 2017 is usually located here: C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer. You will need to create one additional folder named Ide inside the Team Explorer folder Then you can copy the vsdiffmerge.exe file from the Team Explorer folder to the newly created Ide folder. You can check the attached vsdiffmerge-path.png screenshot.

Then you can create the environment variable like this:
Variable name: VS120COMNTOOLS
Path: C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer\IDE

VS 2022 17.5.1 successfully converts a blank WinForms project without any Telerik control in it.

VS 2022 17.6.2  hangs:

1. Create clean WinForms .NET Framework project.
2. Add Telerik UI for WinForms 2026.2.520.462.
3. Create BaseForm : RadForm.
4. Add RadStatusStrip to BaseForm.
5. Create inherited form RadForm1 : BaseForm.
6. Open inherited form in Visual Studio designer.
7. Designer crashes with NullReferenceException in Telerik.WinControls.UI.Design.RadControlDesigner.OnSetCursor.
8. Remove/comment RadStatusStrip from BaseForm.Designer.cs.
9. Designer opens successfully.

Sample project attached.

 

On 125% dpi:

 However, if you close the list and open it again, the list has the correct height (the gap is gone).

When we set a checkbox with the CheckState to Indeterminate, then it's serialized by the designer is that order (because VS serialized in alphabetical order).
But next time we open the form, it's unchecked, because setting to Indeterminate before setting IsThreeState to true is ignored.

An exception is thrown when loading a document:

FileNotFoundException: Could not load file or assembly 'Microsoft.Web.WebView2.WinForms, Version=1.0.3719.77, Culture=neutral, PublicKeyToken=2a8ab48044d2601e' or one of its dependencies. The system cannot find the file specified.

In this particular scenario, we have 2 monitors. One with 100 % and one with 150% DPI. When the ScreenTip is shown in 100%, its size is correct. Then if we move the Form to the second monitor that is 150%, the screenTip size is not scaled when shown for the first time. We need to move the mouse to hide and show it again. The second time, the size is correct.

When an appointment has a very short duration (seconds-level, e.g., 1 second and 0 minutes), it does not appear in the RadPrintPreviewDialog. The appointment is visible in the scheduler UI but missing from the print preview.

For example:

Dim ap1 As New Appointment
ap1.Start = New Date(Date.Today.Year, Date.Today.Month, Date.Today.Day, 15, 0, 0)
ap1.End = New Date(Date.Today.Year, Date.Today.Month, Date.Today.Day, 15, 0, 1)
ap1.Description = "not printed"
ap1.Summary = "not printed"
RadScheduler1.Appointments.Add(ap1)

Incorrect calculation of indentation when a paragraph in a list has applied tab space during PDF export.

The AccessibleName property is not respected by the Windows Narrator.

Clients with perpetual license may observe the following warning when using UI.for.WinForms.AllControls.Net90 (v.2026.1.415): 

Telerik and Kendo UI Licensing warning TKL403: Services associated with Telerik Document Processing Libraries version 2026.1.402.80 require a subscription or trial license. Please obtain a subscription license at https://prgress.co/3PwQMKZ

Telerik and Kendo UI Licensing warning TKL004: Unable to locate licenses for all products.

************** Exception Text **************
System.InvalidOperationException: Invoke or BeginInvoke cannot be called on a control until the window handle has been created.
   at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
   at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
   at System.Windows.Forms.Control.Invoke(Delegate method)
   at Telerik.WinControls.UIAutomation.RadControlBaseRootUIAutomationProvider`1.get_BoundingRectangle()
   at Telerik.WinControls.UIAutomation.Window.RadFormUIAutomationProvider.Form_Resize(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnResize(EventArgs e)
   at System.Windows.Forms.Form.OnResize(EventArgs e)
   at System.Windows.Forms.Control.OnSizeChanged(EventArgs e)
   at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width, Int32 height, Int32 clientWidth, Int32 clientHeight)
   at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width, Int32 height)
   at System.Windows.Forms.Control.SetBoundsCore(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at System.Windows.Forms.Form.SetBoundsCore(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at Telerik.WinControls.UI.RadFormControlBase.SetBoundsCore(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at System.Windows.Forms.Control.SetBounds(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at System.Windows.Forms.Control.set_Size(Size value)
   at Telerik.WinControls.RadMessageBoxForm.SetSizeAndLocations()
   at Telerik.WinControls.RadMessageBoxForm.SetLabelTextAndSize(String text)
   at Telerik.WinControls.RadMessageBoxForm.set_MessageText(String value)
   at Telerik.WinControls.RadMessageBox.ShowCore(IWin32Window owner, String text, String caption, MessageBoxButtons buttons, Bitmap icon, MessageBoxDefaultButton defaultButton, RightToLeft rightToLeft, String detailsText)
   at dummyReader.FormMain.radButtonLogin_Click(Object sender, EventArgs e)
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at Telerik.WinControls.RadControl.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonBase.buttonElement_Click(Object sender, EventArgs e)
   at Telerik.WinControls.RadElement.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonItem.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonElement.OnClick(EventArgs e)
   at Telerik.WinControls.RadElement.DoClick(EventArgs e)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.DoMouseUp(MouseEventArgs e)
   at Telerik.WinControls.ComponentInputBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.RadControl.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadButton.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

The reported behavior is observed in VisualStudio2022Light (or dark), VisualStudio2012, Office2013, Windows11.

When the BestFitColumns() method is used, the column width will be calculated to fit the content. In a scenario where the content is the longest one in the column, it will be next to the left and right side cell borders. When such a cell is selected and marked as a current cell, the current cell border will be applied, which will shrink the space for the content, and ellipses will appear.

The BestFitColumns() method needs to take into account the current cell border width in different themes.

Pressing the F1 key opens the broken link in the documentation. The correct one is : https://www.telerik.com/products/winforms/documentation/tools/visual-style-builder/overview 
 

In this scenario, we are using the custom approach from the How to Change PageViewMode for the Nested Levels in RadGridView KB article. When a child row is expanded and we collapse and expand its parent, an exception is thrown.

Hi support,

I think I found an issue with the default behavior of Telerik UI for Winforms on a HighDPI PerMonitorV2 configuration.

The application works correctly and resizes well if moved between screen with different Font Scalings.

However, if the user changes the main screen to one with a different scaling, the application is strangely taking the change into account and would also not come back to its original state.

Attached is a GIF showing the problem and the project. The application on run on screen 3 being main display at 100% FontScale. If I pass Screen 1, the main display (which is 125% font scaled), the icons of the app are made larger (for no reason), going back to screen 1 being the main screen, will not restore the icon to the correct size, unless you make parts of the application being redrawn.

I've a more related question but it's more complex and I won't be able to provide a project for this, so I'm just trying here ;) In our real application (not this test one), when setting PerMonitorV2 mode, we need to have RadControl.EnableRadAutoScale set to false for the controls to resize correctly when changing monitors whereas this [test] application needs it to be let it set to true to kind of do the same thing ?! Any idea on where the difference can come from ?

Thanks & regards,

Benjamin Foucher