While performing Cut operation inside RadDiagram, an exception in the MS Clipboard occurs with the following message:

System.Runtime.InteropServices.COMException: 'OpenClipboard Failed (Exception from HRESULT: 0x800401D0 (CLIPBRD_E_CANT_OPEN))'

Currently large diagrams are hard to export with good quality because of the memory limitation in WritableBitmap when the DPI is increased.

 -- One option is to use BitMapCacheBrush (discussed here http://www.telerik.com/forums/low-resolution-using-exporttoimage-on-big-diagram)

 -- Another option is to export multiple images of the diagram which cover it all. Then possibly combine these pictures into one.

 -- Also , you can try increasing the operating memory of your Visual Studio

If we have a custom shape that derives from RadDiagramShapeBase and we rotate it at some degree (90) for example, and then resize it the diagram's selection adorner is misplaced with the shape.

Workaround:
Set RenderTransofrmOrigin = new Point(0.5, 0.5) to the shape.
Other workaround:
Derive the custom shape from RadDiagramShape, instead of RadDiagramShapeBase. 

In DiagramRibbon the buttons, numerics, combos, selectors which are not bound to Diagram or DiagramRibbon Commands, fail to execute their actions in Simplified mode.

An API could be created so that an Image can be added to the Background or Grid of the Diagram so that the user can zoom and pan over the image.

Setting ContainerMargin constant to 0 will make the margin 0 on the left, bottom and right side of the content. However, the shapes in the content of the container, will overlap its header. Expected is child shapes do not overlap any borders in the container.

Add API so that the user can prevent the auto close popup wrapper behavior.

Support out of the box Fishbone diagram.

To reproduce this use the following code snippet:

Steps to reproduce:

1. Start a new connection from Shape 1, by dragging one of its connectors.
2. Drag the connection over Shape 2. 

Expected: The connector closest to the mouse should get highlighted and when you drop the connection it should get attached to the shape.
Actual: The closest connector is not highlighted. Also, when you drop the connection over the target shape it doesn't get attached.

The exception is thrown for the RotationAngle property.

The issue can be observed also in the opposite direction - the diagram is serialized on a machine with some culture (for example Portugal Porguese - pt-PT) and then restored on a machine with an English culture.

The issue reproduces only when saving and loading between cultures which numeric separators are different. For example, with Bulgarian culture, the number 4.5 is represented as 4,5 (with a comma). With English culture the number will be represented as 4.5 (with a period).

To work this around, create a custom RadDiagramShape and override its Deserialize() method. Then parse the RotationAngle manually, and set it to the RotationAngle property of the shape. After this, set the RotationAngle of the SerializationInfo to null, in order to prevent the default restoring of the property.

Currently, the print preview control provides only options for the current printer, the page orientation and the page size . Include the following options too:

 - Paper Format (Lettre, A4, etc.)
 - Paper Orientation (Portrait or Landscape)
 - Number of copies (1, 2, 3, ...)
 - Print Color Settings (Colors or Monochrome)
 - Margins
 - Resolution (DPI based on the capabilities of the printer)

When zooming out on more than 500-600 shapes and then panning, if telerik:DiagramSurface.IsVirtualizing="True", the performance is slower. 

When virtualization is off, the performance is a little better.

Connect the Diagrams BackgroundGrid to the Ruler's Measurement Unit and ScaleDefinitions.

Currently only in DPI measurement unit the scaledefinitions and diagram background grid look good and consistent.

A possible workaround is to use an attached property. Basically, we've added ConnectionPointsProperty in AttachedProperties class and added binding to this new property in the style of the connection.

public class AttachedProperties
    {
        public static RadDiagram Diagram { get; set; }

        public static readonly DependencyProperty ConnectionPointsProperty =
           DependencyProperty.RegisterAttached("ConnectionPoints", typeof(List<Point>), typeof(AttachedProperties), new PropertyMetadata(null, OnConnectionPointsChanged));

        public static IEnumerable<Point> GetConnectionPoints(DependencyObject obj)
        {
            return (IEnumerable<Point>)obj.GetValue(ConnectionPointsProperty);
        }

        public static void SetConnectionPoints(DependencyObject obj, IEnumerable<Point> value)
        {
            obj.SetValue(ConnectionPointsProperty, value);
        }

        private static void OnConnectionPointsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var connection = d as RadDiagramConnection;
            var connectionPoints = e.NewValue as List<Point>;
            if (connection != null && connectionPoints != null)
            {
                for (int i = 0; i <  connectionPoints.ToList().Count; i++)
                {
                    connection.ConnectionPoints.Add(connectionPoints.ToList()[i]);                 
                }
                connection.IsModified = true;
                (connection as IConnection).Update();
            }
        }
    }



  <telerik:RadDiagram.ConnectionStyle>
                <Style TargetType="telerik:RadDiagramConnection">
                    <Setter Property="ConnectionType" Value="Polyline"/>
                    <Setter Property="local:AttachedProperties.ConnectionPoints" Value="{Binding MyConnectionPoints}"/>
                </Style>
            </telerik:RadDiagram.ConnectionStyle>

The undo and redo actions don't work for the "Move Items" event. This means that nothing will happen when you select a Bezier connection (ConnectionType=Bezier) and drag/drop it to a new position, then press Ctrl+Z.

When executing the DiagramCommands.Nudge command with a provided number as a parameter, the movement of the selected shape is incorrect. 

You should be able to prevent the horizontal/vertical overlapping of routed connections . This way the connections should be easier to differentiate.

To better differentiate connections, users might:

            --- use labels on the connections

            --- use bezier connections

            --- use different colors for different connections

            --- use more custom connectors and attach the connections to not used connectors

            -- use AStartRouter instead of the default one (Grid Router)

This feature is available with our latest official version - R1 2019.

Be able to pre-select, printer, page size and page orientation in the RadDiagramPrintPreview. By default, RadDiagramPrintPreview set the printing orientation in landscape even if we created a diagram in portrait. 

A small glitch appears when the pencil tool is used. The glitch is demonstrated in the attached image.