RadDiagram provides 3 Mouse Tools that determine the actions you can perform with your mouse - Pointer Tool, Connector Tool and Pan Tool.
Below you can find sample descriptions of the three Mouse Tools:
Pointer Tool - this is the default(active) tool. Allows you to drag, select, resize items and etc.
Connector Tool - it is partially active. Allows you to create connections. In order to create floating connections, you have to set the RadDiagram.ActiveTool to ConnectorTool.
Pan Tool - it is not active. Allows you to perform panning. You can activate it by pressing the Control Key. When active, the Pointer Tool and Connector tool are disabled.
Please note that you can set the active tool in XAML or code behind using the ActiveTool property. But since the PanTool could be activate by pressing the Ctrl key, this makes sense only if you set the ActiveTool to ConnectorTool - which will allow you to create floating connections.