private void RadBarcode_Loaded(object sender, RoutedEventArgs e)
{
    var barcode = (RadBarcode)sender;
    var desiredWidth = 250;
    double relativeWidthDelta = desiredWidth / barcode.ActualWidth;
    barcode.LayoutTransform = new ScaleTransform() { ScaleX = relativeWidthDelta };
}

System.ArgumentException: '8' is not a valid value for property 'Width'.
   at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
   at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
   at Telerik.Windows.Media.Imaging.Commands.DrawCommand.Execute(RadBitmap source, Object context)
   at Telerik.Windows.Media.Imaging.History.ImageHistory.Execute(IImageCommand command, Object context)
   at Telerik.Windows.Controls.RadImageEditor.ExecuteCommand(IImageCommand command, Object context)
   at Telerik.Windows.Controls.RadImageEditor.CommitTool(Boolean executeSameToolAfterCommit)
   at Telerik.Windows.Media.Imaging.Tools.DrawToolBase.InvokeEndDraw(Point point)
   at Telerik.Windows.Media.Imaging.Tools.DrawToolBase.DrawingCanvas_MouseLeftButtonUp(Object sender, MouseButtonEventArgs e)

public class CustomDrawTool : DrawTool
{
    public override IImageCommand GetCommand()
    {
        return new CustomDrawCommand();
    }
}

public class CustomShapeTool : ShapeTool
{
    public override IImageCommand GetCommand()
    {
        return new CustomDrawCommand();
    }
}

public class CustomDrawCommand : IImageCommand
{
    public RadBitmap Execute(RadBitmap source, object context)
    {
        DrawCommandContext drawCommandContext = context as DrawCommandContext;
        if (drawCommandContext == null || drawCommandContext.DrawnPath == null)
        {
            return source;
        }

        Canvas canvas = new Canvas();

        canvas.ClipToBounds = true;
        var dpiXFactor = source.Bitmap.DpiX / 96;
        var dpiYFactor = source.Bitmap.DpiY / 96;

        double imageWidth = source.Width / dpiXFactor;
        if (imageWidth == double.PositiveInfinity)
        {
            imageWidth = source.Width;
        }
        double imageHeight = source.Height/ dpiYFactor;
        if (imageHeight == double.PositiveInfinity)
        {
            imageHeight = source.Height; 
        }

        canvas.Children.Add(new System.Windows.Controls.Image()
        {
            Source = source.Bitmap,
            Width = imageWidth,
            Height = imageHeight,
        });

        Panel parent = drawCommandContext.DrawnPath.Parent as Panel;
        if (parent != null)
        {
            parent.Children.Remove(drawCommandContext.DrawnPath);
            drawCommandContext.DrawnPath.RenderTransform = new ScaleTransform(1 / dpiXFactor, 1 / dpiYFactor);
            canvas.Children.Add(drawCommandContext.DrawnPath);
        }

        RenderOptions.SetBitmapScalingMode(canvas, BitmapScalingMode.NearestNeighbor);
        BitmapSource bitmapSource = this.GetBitmapSource(source.Width, source.Height, canvas, source.Bitmap.DpiX, source.Bitmap.DpiY);
        return new RadBitmap(bitmapSource);
    }

    private BitmapSource GetBitmapSource(int width, int height, Canvas canvas, double dpiX, double dpiY)
    {
        Size size = new Size(width, height);
        canvas.Measure(size);
        canvas.Arrange(new Rect(size));
        RenderTargetBitmap renderBitmap = new RenderTargetBitmap(width, height, dpiX, dpiY, PixelFormats.Pbgra32);
        renderBitmap.Render(canvas);
        return renderBitmap;
    }
}

  <telerik:ImageToolItem ImageKey="Draw" telerik:LocalizationManager.ResourceKey="ImageEditor_Draw" Command="commands:ImageEditorRoutedCommands.ExecuteTool">
      <telerik:ImageToolItem.CommandParameter>
          <local:CustomDrawTool />
      </telerik:ImageToolItem.CommandParameter>
  </telerik:ImageToolItem>

Exception Info: System.Net.Sockets.SocketException
  at System.Net.Sockets.NetworkStream.Read(Byte[], Int32, Int32)
Inner Exception:
Exception Info: System.IO.IOException
  at System.Net.ConnectStream.Read(Byte[], Int32, Int32)
  at System.IO.Stream.InternalCopyTo(System.IO.Stream, Int32)
  at Telerik.Windows.Documents.Layout.ExtensionMethods.ToMemoryStream(System.IO.Stream)
  at Telerik.Windows.Documents.Model.ImageInline.<SetStreamFromUriSource>b__0(System.Object, StreamReadyEventArgs)
  at Telerik.Windows.Documents.Utils.ResourceStreamLocator.OnStreamReady()
  at System.Net.WebClient.OnOpenReadCompleted(System.Net.OpenReadCompletedEventArgs)
  at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
  at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
  at System.Windows.Threading.DispatcherOperation.InvokeImpl()
  at MS.Internal.CulturePreservingExecutionContext.CallbackWrapper(System.Object)
  at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
  at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
  at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
  at MS.Internal.CulturePreservingExecutionContext.Run(MS.Internal.CulturePreservingExecutionContext, System.Threading.ContextCallback, System.Object)
  at System.Windows.Threading.DispatcherOperation.Invoke()
  at System.Windows.Threading.Dispatcher.ProcessQueue()
  at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
  at MS.Win32.HwndWrapper.WndProc(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
  at MS.Win32.HwndSubclass.DispatcherCallbackOperation(System.Object)
  at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
  at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
  at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority, System.TimeSpan, System.Delegate, System.Object, Int32)
  at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr, Int32, IntPtr, IntPtr)
  at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
  at System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame)
  at System.Windows.Application.RunDispatcher(System.Object)
  at System.Windows.Application.RunInternal(System.Windows.Window)

 private void RadRibbonBackstage_Loaded(object sender, RoutedEventArgs e)
 {
     var backstage = (RadRibbonBackstage)sender;
     var closeButton = backstage.FindChildByType<RadRibbonButton>();
     closeButton.Margin = new Thickness(closeButton.Margin.Left, 15, closeButton.Margin.Right, closeButton.Margin.Bottom);
 }