How To Prevent the Nodes From Being Rotated

This can be done by raising the Diagram.Model.EventSink.RotationChanging event and canceling the operation.

this.diagram1.Model.EventSink.RotationChanging += new RotationChangingEventHandler(EventSink_RotationChanging); 

void EventSink_RotationChanging(RotationChangingEventArgs evtArgs) 

{ 

    evtArgs.Cancel = true; 

}
Me.diagram1.Model.EventSink.RotationChanging += New RotationChangingEventHandler(EventSink_RotationChanging) 

Private Sub EventSink_RotationChanging(ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.RotationChangingEventArgs)

evtArgs.Cancel = True

End Sub