There are is no build in setting which you could set to make change that behavior. However you could easily make the Shape to be positioned based on the requirement. You could use one of the following approaches:
- If you are in MVVM scenario and you want to Position the shapes based on the center of the shape you could bind the Position/Width/Height properties of the shape. Then calculate the position based on the Width and Height of the shape and make the modification you need. But in the end the Position still will be the TopLeft of the shape.
- another approach is to inherit the RadDiagramShape and extend it. You could do that by creating a new property CenterPosition which internally uses the position and the Width/Height of the shape.
I have attached a sample project demonstrating the second approach. I hope this information helps. Please let us know if you need further assistance.