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)

-- Add ClearCache method to clear the undo-redo dictionaries used internally

or

-- make the undo-redo dictionaries auto clear when undo-redo stacks are cleared

Available in LIB version: 2016.3.1114
Clear method of Diagram's UndoRedoService now clears the UndoRedo internal cache automatically.  
What's changed ? The public interface IDiagramContainerGeneratorInternal interface now adds ClearCache method:
A) this.Diagram.UndoRedoService.Clear(); will clear the internal undoredo cache which stores model-container relations. Also this will clear the undo/redo command stacks.
B) this.Diagram.ContainerGenerator as GenericContainerGenerator<RadDiagramItem>).ClearCache(); will clear ONLY the undoredo cache.

Introducing Page size (A4, etc) concenpt and vertical and horizontal rulers

Implement automatic-layout of Polytree (http://en.wikipedia.org/wiki/Polytree) graphs.
Layout with multiple roots in single graph component.

We added an SDK sample showing how you can layout such tree hierarchies in RadDiagram:
https://github.com/telerik/xaml-sdk/tree/master/Diagram/MultipleRootsInSingleTreeLayout 

When you start resize operation on a grouped ContainerShape and Shape in it the Container shape size can not be shrink-ed more than the previous BottomRight position of the shape in it (despite that the shape size is changed and there is space for the collapsing).


Available in LIB version: 2016.1.21

A stackOverflow exception is thrown when the diagram is layouted with AStarRouter, Sugiyama and connection bridges.


Available in LIB version: 2015.3.1026 

In data binding scenarios these propeties are not updated automatically. Currently if you want to bind the StartPoint and EndPoint properties of the RadDiagramConnection you will have to update new position of the connection manually. This can be done in the PropertyChanged event of the connection. In the Handler you can cast your connection to IConnection and call the Update() method, if the e.PropertyName holds the property that you change.

Will be available in Q1 2015 Release.

Issues when drawing with diagram drawing tools on win8 touch device. Drawing is not smooth - it is very angular and slow. 

Available in LIB version: 2014.3.1409

RadContextMenu is set on DiagramShape. On touch device, you cannot open the ContextMenu with Tap and hold gesture.

Available in LIB version: 2014.3.1409

Allow the user to customize the caps (SourceCapType and TargetCapType) of the connection.

Exposed are  two new virtual methods in the RadDiagramConnection - CreateSourceCapGeometry and CreateTargetCapGeometry

Available in Q1 2015

Expose a property to set the DiagramBehaviors.TextWrapping attached property on a diagram level

On graphSouce change the graphSource's collectionChanged event is not detached and because of this the diagram will still create shapes if you add items to it.

Fixed in LIB version: 2014.2.0804

Can't paste a connection in a diagram different than the original one - the one in which the copy operation was executed.

User sometimes need to use a Static Ruler which does not scale when you zoom the Diagram. Or when you pan. Just line with star 0, ticks, end 1024 for example. This line does not move and does nto scale.

There is no easy way to achieve this. UpdateScale method is private. It could be protected.

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In Q1 2014 SP DiagamRuler will draw itself and its ticks when its Diagram property is NOT set.

Implement functionality that notifies the user when a shape is dragged out of a container.

Diagram Shapes' property is bound to property from the ViewModel.
Case 1) Using GraphSource =>Shapes DataContext is automatically apllied. GraphSource is set to null or changed.
Or
Case 2) Not using Graphsource. Shape's DataContext is set manually (in code behind). Diagram.Clear() is invoked.


Result: Binding Expression errors in Output indicate missing properties - these are bound properties of the shapes.

Inherit RadDiagramConnector and add it to a Shapes' Connectors collection. Copy / Pasting (or other serialization / deserialization action) the shape creates RadDiagramConnector, not the custom type of connector.

ManipulationAdorner (including Rotation thumb, resizing thumbs) should not be zoomed along with the shape.

Currently the Bezier Connections Start,End Points and the two editing points are created in a common Canvas. There is no mechanism to hide the editing points but show the start and end point.
Note: Currently there's a way to hide editing or intermediate points - you'll need a style and a converter. We've added a new SDK example (HideBezierHandles) demonstrating this.

Users should be able to easily customize the Pan operation of the diagram.
Update: With Q1 2014 you'll be able to customize all the diagram tools