As a workaround, the property can be set locally for the time being.

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

Reason for Declination: This feedback item is duplicate with the one below: 
http://feedback.telerik.com/Project/143/Feedback/Details/67148-implement-item-to-item-snapping-during-resize
Please follow and vote for it instead.

When you select the Size tab and than select another shape where the Size should not be available, its content is shown whether is enabled or not. The SettingsPane should fallback to an enabled tab when one is disabled.

To work this around you can create a custom RadTabControl and implement custom fallback selection logic there. Then replace the RadTabConrol from the ControlTemplate of the SettingsPaneView with the custom tab control. Check the attached project.

RadDiagram with virtualization turned off.

Randomly positioned 5000 shapes are added in Diagram.

For the test, Shapes are with simplified template consisting pretty much of a single Border and nothing else.

On maximized WPF window, Diagram Load for about 3-3.5 seconds.

On normal WPF window, DIagram loads for about 15 seconds.

Currently, when you select multiple shapes, you can rotate them altogether using the rotate icon displayed on top of the ManipulationAdorner visual (the rectangle that encloses the shapes). However, there is no property or a method that allows to programmatically provide a rotation angle for the adorner. 

Add a RotationAngle property or a Rotate() method or something similar that will automatically update the rotation of the ManipulationAdorner along with the shapes inside.

Loading the diagram via its Load() method adds additional "Copy of" to the GroupName property of the groups.

Use TextTool to create shape with no text but with background.

Pressing enter will close the tool. But the shape remains visible, but you cannot neither select it nor delete it with mouse / keyboard.
By design this shape should be removed both from the Shapes collection and from the diagram surface.

As a workaround you can try deleting this shape manually by overriding the Diagram's CommandExecuted event :

 private void diagram_CommandExecuted(object sender, CommandRoutedEventArgs e)
        {
            if (e.Command.Name == "Edit Item")
            {
                foreach (RadDiagramTextShape textShape in this.diagram.ChildrenOfType<RadDiagramTextShape>())
                {
                    if (!this.diagram.Shapes.Contains(textShape))
                    {
                        Canvas parent = textShape.Parent as Telerik.Windows.Controls.Diagrams.DiagramSurface;
                        if (parent != null)
                        {
                            parent.Children.Remove(textShape);
                            this.diagram.ServiceLocator.GetService<Telerik.Windows.Diagrams.Core.ISelectionService<IDiagramItem>>().ClearSelection();
                        }
                    }
                }
            }

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

Memory leak when you close a window that holds a RadDiagram. The RadDiagram and its shapes are not cleared.

If you delete a RadDiagramShape property using the SettingsPane (e.g. StrokeThickness) and then you try to call RadDiagram.Save() method, the generated string is not in the correct format. The deleted property is set to Auto in the string, while it should be set to 0.
Hence, if you try to load the same string, the RadDiagram throws FormatException.

Available in LIB version: 2014.3.1208

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

XAML connections' Source and Target bindings don't work inside tab control if the diagram is not in the first TabItem.

There's a new attached property in the DiagramBehaviors - NameScopeProvider in WPF. It can be set to the RadDiagram by given element that holds the current NameScope (it's usually the root element - Window or UserControl). 

Example:
<telerik:RadDiagram x:Name="diagram"
telerik:DiagramBehaviors.NameScopeProvider="{Binding ElementName=root}"       ... />

Setting diagram.UndoRedoService.UndoBufferSize to 0 after doing some undoable action in diagram does not stop the undo operations.

This is a regression issue. 

Expected: 
UndoBufferSize 0 means no undo possible.  
RedoBufferSize 0 means no redo possible.

Worakround if applicable: Set the UndoBufferSize to 0 after InitializeComponent. (this is if you don't need undo/redo at all).

Editing any diagram shape does not take into account the fontsize of the shape.

A possible workaround is to wire to shape's Loaded event as below:
private void RadDiagramTextShape_Loaded(object sender, RoutedEventArgs e)
        {
            RadDiagramTextShape shape = sender as RadDiagramTextShape;
            TextBox tBox = shape.ChildrenOfType<TextBox>().FirstOrDefault();
            tBox.FontSize = shape.FontSize;
        }


Available in LIB version: 2016.3.926

The AllowPaste property does not work in MVVM scenario. The DeserializeNode() method in the GraphSource is called.

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

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