Using button in order to pan the diagram is not supported out of the box. You can achieve this behavior using custom implementation. Basically, you can subscribe to the MouseDown and MouseUp events of the RadDiagram. In the event handlers, you can check the current press button and change the property of the diagram.
For your convenience, I have created sample project which demonstrates this approach. You can additionally modify this project so it fits in your main application.
Regards,
Dinko
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