************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinForms.Documents.UI.UIProviders.WatermarkUIProvider.Arrange(UILayerUpdateContext uILayerUpdateContext)
   at Telerik.WinForms.Documents.UI.Layers.ProviderUILayerBase.ArrangeChildren()
   at Telerik.WinForms.Documents.UI.DocumentPrintPresenter.ArrnageUILayers()
   at Telerik.WinForms.Documents.UI.DocumentPrintPresenter.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureChildren(SizeF availableSize)
   at Telerik.WinControls.RichTextEditor.UI.FrameworkElement.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.Layouts.ContextLayoutManager.UpdateLayout()
   at Telerik.WinForms.Documents.UI.DocumentPrintPresenter.Telerik.WinForms.RichTextEditor.IDocumentEditorPresenter.UpdateLayout()
   at Telerik.WinForms.RichTextEditor.RadRichTextBox.<>c__DisplayClass3.<UpdateEditorLayout>b__2()
   at Telerik.WinForms.RichTextEditor.RadRichTextBox.UpdateEditorLayout(Boolean focusCarret, Boolean updateCaretSize, Boolean async)
   at Telerik.WinForms.RichTextEditor.RadRichTextBox.set_ActiveEditorPresenter(IDocumentEditorPresenter value)
   at Telerik.WinForms.RichTextEditor.RadRichTextBox.Telerik.WinControls.UI.IPrintable.BeginPrint(RadPrintDocument sender, PrintEventArgs args)
   at Telerik.WinControls.UI.RadPrintDocument.OnBeginPrint(PrintEventArgs e)
   at System.Drawing.Printing.PrintDocument._OnBeginPrint(PrintEventArgs e)
   at System.Drawing.Printing.PrintController.Print(PrintDocument document)
   at System.Drawing.Printing.PrintDocument.Print()
   at System.Windows.Forms.PrintPreviewControl.ComputePreview()
   at System.Windows.Forms.PrintPreviewControl.CalculatePageInfo()
   at System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme)
   at System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme)
   at System.Windows.Forms.Control.InvokeMarshaledCallbacks()


To reproduce: please refer to the attached gi file demonstrating how to replicate the problem with the Demo application.

Workaround:

        private void radRichTextEditor1_CommandExecuting(object sender, Telerik.WinForms.Documents.RichTextBoxCommands.CommandExecutingEventArgs e)
        {
            if (e.Command  is ChangeIntegratedWatermarkTypeCommand && this.radRichTextEditor1.LayoutMode!= Telerik.WinForms.Documents.Model.DocumentLayoutMode.Paged)
            {
                e.Cancel = true; 
            }
        }