In the Visual Theme Builder (fresh installed Telerik UI for WinForms) you'll get an error because the directory "VbsRecoveryData" seems to be missing. Creating the directory before "package.Compress(path)" fixes this for me.

When Telerik UI for WinForms / WPF extensions are installed, Visual Studio is unresponsive for a couple of minutes after a solution is loaded. During that time, "Updating source control status…" is shown.

Workarounds:

• Disable Telerik UI for WinForms / WPF extensions.
• Checkout the solution file.

On the second opening, it corrects:

Hello,

We encountered problems with configuration of the toolbox in Visual Studio 2022 when out-of-proc designer is active.
More information about the usage and reason for the out-of-proc designer: https://github.com/dotnet/winforms/blob/main/docs/designer/designer-selection.md

Tested environment:
- Visual Studio 2022
- .NET Framework 4.7.1
- 32-bit application
- Windows 11 Pro
- Telerik UI For Winforms 2025.2.520.462

When trying to add a rad control from the toolbox the error in attachment occurs.

Workaround:
- Disable the out-of-proc designer in the project file:

<UseWinFormsOutOfProcDesigner>False</UseWinFormsOutOfProcDesigner>

Implement Text to Columns functionality similar to the one in Excel:

Error is received when click on button. Reproduced randomly on different machines.

Since 2025 Q2 you'll get this error message when you try to open a flyout on a control that is not a Form. This does not happen with 2025 Q1.

Might be related: https://feedback.telerik.com/winforms/1688619-radform-clientsize-on-inherited-radform-is-broken

However, this time I have no patch / workaround. I have not the time to investigage deeper at the moment, so update to Q2 not possible for me at the moment.

 This issue starts happening as of Q2 (2025.2.520) version.

Workaround: override SetClientSizeCore() inside of inherited RadForm

public partial class RadForm2 : RadForm1
{
    protected override void SetClientSizeCore(int x, int y)
    {
        base.SetClientSizeCore(x, y);

        if ((!this.IsLoaded || !this.IsHandleCreated) &&
            this.IsInitialized)
        {
            MethodInfo mi = typeof(Form).GetMethod("SetClientSizeCore", BindingFlags.NonPublic | BindingFlags.Instance);
            if (mi != null)
            {
                IntPtr ptr = mi.MethodHandle.GetFunctionPointer();
                Action<int, int> baseSetClientSizeCore = (Action<int, int>)Activator.CreateInstance(
                    typeof(Action<int, int>), this, ptr);

                baseSetClientSizeCore.Invoke(x, y);
            }
        }
    }
}

Add a call to "OnImageLoaded" to "RadPictureBoxelement.PasteImage()" method or create an event like "ImagePasted" ot be able to tract an image change at this point.

For me I solved this via an Harmony patch that adds a call to OnImageLoaded() on PasteImage()  long time ago. Not really elegant, but I'm a noob in patching with Harmony.

Just want to leave it here for anyone that want ot use this solution too or for Telerik to implement a native way to expose an image change via PasteImage.

[HarmonyPatch(typeof(RadPictureBoxElement))]
[HarmonyPatch("PasteImage")]
public class RadPictureBoxElement_PasteImageFixes
{
    private static readonly Dictionary<RadPictureBoxElement, Image> images = [];

    public static void Prefix(object __instance)
    {
        if (__instance is RadPictureBoxElement pb)
        {
            // Remember our image
            images.Remove(pb);
            images.Add(pb, pb.Image);
        }
    }

    public static void Postfix(object __instance)
    {
        if (__instance is RadPictureBoxElement pb && images.TryGetValue(pb, out var image) && pb.Image != image)
        {
            // Remove first to avoid conflicts on error
            images.Remove(pb);

            // Call "OnImageLoaded"
            var method = typeof(RadPictureBoxElement).GetMethod("OnImageLoaded", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
            method.Invoke(pb, null);
        }
    }
}