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.

PathTool: Possibility to edit the shape path via edit points like the Pen Tool in Blend.

Extend RadDiagram to support natively Venn Diagrams.

Extend the layout mechanism to allow control over the layouted elements in order to exclude all disconnected shapes from the layout and reorder connections by their target connectors.

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.

Currently there is no straightforward way to notify that a point is added/removed from the ConnectionPoints collection of the RadDiagramConnection.

There should be annotations (comments) system built into the framework:
€¢something like Word where one can add to a word a note
€¢something like Excel with its comments bag
€¢something like Workflow Foundation where every shape has a popup bag

Import from DWG files needed.

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>

Implement "Item to Item Snapping" during item resize operation.

Add ContainerShape ContentTemplate and ContentTemplateSelector properties in RadDiagram

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. 

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)

We use a RadDiagram for what is essentially graphic-art layout.  At times, subpixel positioning and extents really are correct for this use case.  We have shapes correctly positioned and displaying at subpixel accuracy; however, the selection outline always snaps to a pixel.

This is particularly relevant when zoomed in on a piece of art, e.g., aligning semi-transparent edges.  It looks odd to have the selection outline lie outside of the visible extents of the art.  Furthermore, when moving the art by mouse, the interaction is odd in that the art appears to move smoothly while the selection outline pops from pixel to pixel.  This confused our users as to what was really happening as they positioned things.

The relevant code for this is in RadDiagram.UpdateManipulationAdorner, which uses Math.Floor and Math.Ceiling to snap the line to pixel borders.  This was apparently put in to solve issues of blurriness from having a, say, 1-pixel selection outline lie at a sub-pixel position.  Perhaps a dependency property to control whether this snapping happens?

If you have two nested containers and a shape inside the inner container a wrong connector will be activated if you try to create connection (target) to the shape. This can be reproduced with the MVVM SDK example. Try to connect the "Polo" shape to the "Bugatti" shape. The auto connector of the "Bugatti" shape will not be activated when the endpoint of the connection is inside the shape. It will be activated only if you directly hover over the connector.

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

When you paste a big image (bigger than 1024px) it gets blurry

When you switch between two different positions and zoom levels leads to a wrong visualization of the diagram items.